Division of integers with remainder, rules, examples. Dividing integers with a remainder: rules, examples Rule for dividing with a remainder a positive integer by a negative integer, examples

Let's look at a simple example:
15:5=3
In this example natural number We divided 15 completely by 3, without remainder.

Sometimes a natural number cannot be completely divided. For example, consider the problem:
There were 16 toys in the closet. There were five children in the group. Each child took the same number of toys. How many toys does each child have?

Solution:
Divide the number 16 by 5 using a column and we get:

We know that 16 cannot be divided by 5. The nearest smaller number that is divisible by 5 is 15 with a remainder of 1. We can write the number 15 as 5⋅3. As a result (16 – dividend, 5 – divisor, 3 – incomplete quotient, 1 – remainder). Received formula division with remainder which can be done checking the solution.

a= bc+ d
a – divisible,
b - divider,
c – incomplete quotient,
d - remainder.

Answer: each child will take 3 toys and one toy will remain.

Remainder of division

The remainder must always be less than the divisor.

If during division the remainder is zero, then this means that the dividend is divided completely or without a remainder on the divisor.

If during division the remainder is greater than the divisor, this means that the number found is not the largest. There is a greater number that will divide the dividend and the remainder will be less than the divisor.

Questions on the topic “Division with remainder”:
Can the remainder be greater than the divisor?
Answer: no.

Can the remainder be equal to the divisor?
Answer: no.

How to find the dividend using the incomplete quotient, divisor and remainder?
Answer: We substitute the values ​​of the partial quotient, divisor and remainder into the formula and find the dividend. Formula:
a=b⋅c+d

Example #1:
Perform division with remainder and check: a) 258:7 b) 1873:8

Solution:
a) Divide by column:

258 – dividend,
7 – divider,
36 – incomplete quotient,
6 – remainder. The remainder is less than the divisor 6<7.


7⋅36+6=252+6=258

b) Divide by column:

1873 – divisible,
8 – divisor,
234 – incomplete quotient,
1 – remainder. The remainder is less than divisor 1<8.

Let’s substitute it into the formula and check whether we solved the example correctly:
8⋅234+1=1872+1=1873

Example #2:
What remainders are obtained when dividing natural numbers: a) 3 b)8?

Answer:
a) The remainder is less than the divisor, therefore less than 3. In our case, the remainder can be 0, 1 or 2.
b) The remainder is less than the divisor, therefore less than 8. In our case, the remainder can be 0, 1, 2, 3, 4, 5, 6 or 7.

Example #3:
What is the largest remainder that can be obtained when dividing natural numbers: a) 9 b) 15?

Answer:
a) The remainder is less than the divisor, therefore less than 9. But we need to indicate the largest remainder. That is, the number closest to the divisor. This is the number 8.
b) The remainder is less than the divisor, therefore, less than 15. But we need to indicate the largest remainder. That is, the number closest to the divisor. This number is 14.

Example #4:
Find the dividend: a) a:6=3(rest.4) b) c:24=4(rest.11)

Solution:
a) Solve using the formula:
a=b⋅c+d
(a – dividend, b – divisor, c – partial quotient, d – remainder.)
a:6=3(rest.4)
(a – dividend, 6 – divisor, 3 – partial quotient, 4 – remainder.) Let’s substitute the numbers into the formula:
a=6⋅3+4=22
Answer: a=22

b) Solve using the formula:
a=b⋅c+d
(a – dividend, b – divisor, c – partial quotient, d – remainder.)
s:24=4(rest.11)
(c – dividend, 24 – divisor, 4 – partial quotient, 11 – remainder.) Let’s substitute the numbers into the formula:
с=24⋅4+11=107
Answer: c=107

Task:

Wire 4m. need to be cut into 13cm pieces. How many such pieces will there be?

Solution:
First you need to convert meters to centimeters.
4m.=400cm.
We can divide by a column or in our mind we get:
400:13=30(remaining 10)
Let's check:
13⋅30+10=390+10=400

Answer: You will get 30 pieces and 10 cm of wire will remain.

The article examines the concept of dividing integers with a remainder. Let's prove the theorem on the divisibility of integers with a remainder and look at the connections between dividends and divisors, incomplete quotients and remainders. Let's look at the rules when dividing integers with remainders, looking at them in detail using examples. At the end of the solution we will perform a check.

General understanding of division of integers with remainders

Division of integers with a remainder is considered as a generalized division with a remainder of natural numbers. This is done because natural numbers are a component of integers.

Division with a remainder of an arbitrary number says that the integer a is divided by a number b other than zero. If b = 0, then do not divide with a remainder.

Just like dividing natural numbers with a remainder, integers a and b are divided, with b not zero, by c and d. In this case, a and b are called the dividend and divisor, and d is the remainder of the division, c is an integer or incomplete quotient.

If we assume that the remainder is a non-negative integer, then its value is not greater than the modulus of the number b. Let's write it this way: 0 ≤ d ≤ b. This chain of inequalities is used when comparing 3 or more numbers.

If c is an incomplete quotient, then d is the remainder of dividing the integer a by b, which can be briefly stated: a: b = c (remainder d).

The remainder when dividing numbers a by b can be zero, then they say that a is divisible by b completely, that is, without a remainder. Division without a remainder is considered a special case of division.

If we divide zero by some number, the result is zero. The remainder of the division will also be zero. This can be traced from the theory of dividing zero by an integer.

Now let's look at the meaning of dividing integers with a remainder.

It is known that positive integers are natural numbers, then when dividing with a remainder, the same meaning will be obtained as when dividing natural numbers with a remainder.

Dividing a negative integer a by a positive integer b makes sense. Let's look at an example. Imagine a situation where we have a debt of items in the amount of a that needs to be repaid by b person. To achieve this, everyone needs to contribute equally. To determine the amount of debt for each, you need to pay attention to the value of the private s. The remainder d indicates that the number of items after paying off debts is known.

Let's look at the example of apples. If 2 people owe 7 apples. If we calculate that everyone must return 4 apples, after full calculation they will have 1 apple left. Let us write this as an equality: (− 7) : 2 = − 4 (from t. 1) .

Dividing any number a by an integer does not make sense, but it is possible as an option.

Theorem on the divisibility of integers with remainder

We have identified that a is the dividend, then b is the divisor, c is the partial quotient, and d is the remainder. They are connected to each other. We will show this connection using the equality a = b · c + d. The connection between them is characterized by the divisibility theorem with remainder.

Theorem

Any integer can only be represented through an integer and non-zero number b in this way: a = b · q + r, where q and r are some integers. Here we have 0 ≤ r ≤ b.

Let us prove the possibility of the existence of a = b · q + r.

Proof

If there are two numbers a and b, and a is divisible by b without a remainder, then it follows from the definition that there is a number q, and the equality a = b · q will be true. Then the equality can be considered true: a = b · q + r for r = 0.

Then it is necessary to take q such that given by the inequality b · q< a < b · (q + 1) было верным. Необходимо вычесть b · q из всех частей выражения. Тогда придем к неравенству такого вида: 0 < a − b · q < b .

We have that the value of the expression a − b · q is greater than zero and not greater than the value of the number b, it follows that r = a − b · q. We find that the number a can be represented in the form a = b · q + r.

We now need to consider representing a = b · q + r for negative values ​​of b.

The modulus of the number turns out to be positive, then we get a = b · q 1 + r, where the value q 1 is some integer, r is an integer that meets the condition 0 ≤ r< b . Принимаем q = − q 1 , получим, что a = b · q + r для отрицательных b .

Proof of uniqueness

Let's assume that a = b q + r, q and r are integers with the condition 0 ≤ r true< b , имеется еще одна форма записи в виде a = b · q 1 + r 1 , где q 1 And r 1 are some numbers where q 1 ≠ q, 0 ≤ r 1< b .

When the inequality is subtracted from the left and right sides, then we get 0 = b · (q − q 1) + r − r 1, which is equivalent to r - r 1 = b · q 1 - q. Since the module is used, we obtain the equality r - r 1 = b · q 1 - q.

The given condition says that 0 ≤ r< b и 0 ≤ r 1 < b запишется в виде r - r 1 < b . Имеем, что q And q 1- whole, and q ≠ q 1, then q 1 - q ≥ 1. From here we have that b · q 1 - q ≥ b. The resulting inequalities r - r 1< b и b · q 1 - q ≥ b указывают на то, что такое равенство в виде r - r 1 = b · q 1 - q невозможно в данном случае.

It follows that the number a cannot be represented in any other way except by writing a = b · q + r.

Relationship between dividend, divisor, partial quotient and remainder

Using the equality a = b · c + d, you can find the unknown dividend a when the divisor b with the incomplete quotient c and the remainder d is known.

Example 1

Determine the dividend if, upon division, we get - 21, the partial quotient is 5 and the remainder is 12.

Solution

It is necessary to calculate the dividend a with a known divisor b = − 21, incomplete quotient c = 5 and remainder d = 12. We need to turn to the equality a = b · c + d, from here we get a = (− 21) · 5 + 12. If we follow the order of the actions, we multiply - 21 by 5, after which we get (− 21) · 5 + 12 = − 105 + 12 = − 93.

Answer: - 93 .

The connection between the divisor and the partial quotient and remainder can be expressed using the equalities: b = (a − d) : c , c = (a − d) : b and d = a − b · c . With their help, we can calculate the divisor, partial quotient and remainder. This comes down to constantly finding the remainder when dividing an integer of integers a by b with a known dividend, divisor and partial quotient. The formula d = a − b · c is applied. Let's look at the solution in detail.

Example 2

Find the remainder when dividing the integer - 19 by the integer 3 with a known incomplete quotient equal to - 7.

Solution

To calculate the remainder of division, we apply a formula of the form d = a − b · c. By condition, all data are available: a = − 19, b = 3, c = − 7. From here we get d = a − b · c = − 19 − 3 · (− 7) = − 19 − (− 21) = − 19 + 21 = 2 (difference − 19 − (− 21). This example is calculated using the subtraction rule a negative integer.

Answer: 2 .

All positive integers are natural numbers. It follows that division is performed according to all the rules of division with a remainder of natural numbers. The speed of division with the remainder of natural numbers is important, since not only the division of positive numbers, but also the rules for dividing arbitrary integers are based on it.

The most convenient method of division is a column, since it is easier and faster to get an incomplete or simply a quotient with a remainder. Let's look at the solution in more detail.

Example 3

Divide 14671 by 54.

Solution

This division must be done in a column:

That is, the partial quotient is equal to 271, and the remainder is 37.

Answer: 14,671: 54 = 271. (rest 37)

The rule for dividing with a remainder a positive integer by a negative integer, examples

To perform division with a remainder of a positive number by a negative integer, it is necessary to formulate a rule.

Definition 1

The incomplete quotient of dividing the positive integer a by the negative integer b yields a number that is opposite to the incomplete quotient of dividing the moduli of numbers a by b. Then the remainder is equal to the remainder when a is divided by b.

Hence we have that the incomplete quotient of dividing a positive integer by a negative integer is considered a non-positive integer.

We get the algorithm:

  • divide the modulus of the dividend by the modulus of the divisor, then we get an incomplete quotient and
  • remainder;
  • Let's write down the opposite number to what we got.

Let's look at the example of the algorithm for dividing a positive integer by a negative integer.

Example 4

Divide with remainder 17 by - 5.

Solution

Let's apply the algorithm for dividing with a remainder a positive integer by a negative integer. It is necessary to divide 17 by - 5 modulo. From this we get that the partial quotient is equal to 3, and the remainder is equal to 2.

We get that the required number from dividing 17 by - 5 = - 3 with a remainder equal to 2.

Answer: 17: (− 5) = − 3 (remaining 2).

Example 5

You need to divide 45 by - 15.

Solution

It is necessary to divide the numbers modulo. Divide the number 45 by 15, we get the quotient of 3 without a remainder. This means that the number 45 is divisible by 15 without a remainder. The answer is - 3, since the division was carried out modulo.

45: (- 15) = 45: - 15 = - 45: 15 = - 3

Answer: 45: (− 15) = − 3 .

The formulation of the rule for division with a remainder is as follows.

Definition 2

In order to obtain an incomplete quotient c when dividing a negative integer a by a positive b, you need to apply the opposite of the given number and subtract 1 from it, then the remainder d will be calculated by the formula: d = a − b · c.

Based on the rule, we can conclude that when dividing we get a non-negative integer. To ensure the accuracy of the solution, use the algorithm for dividing a by b with a remainder:

  • find the modules of the dividend and divisor;
  • divide modulo;
  • write the opposite of the given number and subtract 1;
  • use the formula for the remainder d = a − b · c.

Let's look at an example of a solution where this algorithm is used.

Example 6

Find the partial quotient and remainder of division - 17 by 5.

Solution

We divide the given numbers modulo. We find that when dividing, the quotient is 3 and the remainder is 2. Since we got 3, the opposite is 3. You need to subtract 1.

− 3 − 1 = − 4 .

The desired value is equal to - 4.

To calculate the remainder, you need a = − 17, b = 5, c = − 4, then d = a − b c = − 17 − 5 (− 4) = − 17 − (− 20) = − 17 + 20 = 3 .

This means that the incomplete quotient of division is the number - 4 with a remainder equal to 3.

Answer:(− 17) : 5 = − 4 (remaining 3).

Example 7

Divide the negative integer - 1404 by the positive 26.

Solution

It is necessary to divide by column and module.

We got the division of the modules of numbers without a remainder. This means that the division is performed without a remainder, and the desired quotient = - 54.

Answer: (− 1 404) : 26 = − 54 .

Division rule with remainder for negative integers, examples

It is necessary to formulate a rule for division with a remainder of negative integers.

Definition 3

To obtain an incomplete quotient c from dividing a negative integer a by a negative integer b, it is necessary to perform modulo calculations, then add 1, then we can perform calculations using the formula d = a − b · c.

It follows that the incomplete quotient of dividing negative integers will be a positive number.

Let us formulate this rule in the form of an algorithm:

  • find the modules of the dividend and divisor;
  • divide the modulus of the dividend by the modulus of the divisor to obtain an incomplete quotient with
  • remainder;
  • adding 1 to the incomplete quotient;
  • calculation of the remainder based on the formula d = a − b · c.

Let's look at this algorithm using an example.

Example 8

Find the partial quotient and remainder when dividing - 17 by - 5.

Solution

To ensure the correctness of the solution, we apply the algorithm for division with a remainder. First, divide the numbers modulo. From this we get that the incomplete quotient = 3 and the remainder is 2. According to the rule, you need to add the incomplete quotient and 1. We get that 3 + 1 = 4. From here we get that the partial quotient of dividing the given numbers is equal to 4.

To calculate the remainder we will use the formula. By condition we have that a = − 17, b = − 5, c = 4, then, using the formula, we get d = a − b c = − 17 − (− 5) 4 = − 17 − (− 20) = − 17 + 20 = 3 . The required answer, that is, the remainder, is equal to 3, and the partial quotient is equal to 4.

Answer:(− 17) : (− 5) = 4 (remaining 3).

Checking the result of dividing integers with a remainder

After dividing numbers with a remainder, you must perform a check. This check involves 2 stages. First, the remainder d is checked for non-negativity, the condition 0 ≤ d is satisfied< b . При их выполнении разрешено выполнять 2 этап. Если 1 этап не выполнился, значит вычисления произведены с ошибками. Второй этап состоит из того, что равенство a = b · c + d должно быть верным. Иначе в вычисления имеется ошибка.

Let's look at examples.

Example 9

The division is made - 521 by - 12. The quotient is 44, the remainder is 7. Perform check.

Solution

Since the remainder is a positive number, its value is less than the modulus of the divisor. The divisor is - 12, which means its modulus is 12. You can move on to the next check point.

By condition, we have that a = − 521, b = − 12, c = 44, d = 7. From here we calculate b · c + d, where b · c + d = − 12 · 44 + 7 = − 528 + 7 = − 521. It follows that the equality is true. Verification passed.

Example 10

Perform division check (− 17): 5 = − 3 (remaining − 2). Is equality true?

Solution

The point of the first stage is that it is necessary to check the division of integers with a remainder. From this it is clear that the action was performed incorrectly, since a remainder equal to - 2 is given. The remainder is not a negative number.

We have that the second condition is met, but not sufficient for this case.

Answer: No.

Example 11

The number - 19 was divided by - 3. The partial quotient is 7 and the remainder is 1. Check whether this calculation was performed correctly.

Solution

Given a remainder equal to 1. He's positive. The value is less than the divider module, which means that the first stage is being completed. Let's move on to the second stage.

Let's calculate the value of the expression b · c + d. By condition, we have that b = − 3, c = 7, d = 1, which means, substituting the numerical values, we get b · c + d = − 3 · 7 + 1 = − 21 + 1 = − 20. It follows that a = b · c + d the equality does not hold, since the condition gives a = - 19.

From this it follows that the division was made with an error.

Answer: No.

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In this article we will look at division of integers with remainder. Let's start with the general principle of dividing integers with a remainder, formulate and prove the theorem on the divisibility of integers with a remainder, and trace the connections between the dividend, divisor, incomplete quotient and remainder. Next, we will outline the rules by which integers are divided with a remainder, and consider the application of these rules when solving examples. After this, we will learn how to check the result of dividing integers with a remainder.

Page navigation.

General understanding of dividing integers with a remainder

We will consider division of integers with a remainder as a generalization of division with a remainder of natural numbers. This is due to the fact that natural numbers are a component of integers.

Let's start with the terms and designations that are used in the description.

By analogy with the division of natural numbers with a remainder, we will assume that the result of division with a remainder of two integers a and b (b is not equal to zero) is two integers c and d. The numbers a and b are called divisible And divider accordingly, the number d – the remainder from dividing a by b, and the integer c is called incomplete private(or just private, if the remainder is zero).

Let us agree to assume that the remainder is a non-negative integer, and its value does not exceed b, that is, (we encountered similar chains of inequalities when we talked about comparing three or more integers).

If the number c is an incomplete quotient, and the number d is the remainder of dividing the integer a by the integer b, then we will briefly write this fact as an equality of the form a:b=c (remaining d).

Note that when dividing an integer a by an integer b, the remainder may be zero. In this case we say that a is divisible by b without a trace(or completely). Thus, division of integers without a remainder is a special case of division of integers with a remainder.

It is also worth saying that when dividing zero by some integer, we are always dealing with division without a remainder, since in this case the quotient will be equal to zero (see the theory section of dividing zero by an integer), and the remainder will also be equal to zero.

We’ve decided on the terminology and notation, now let’s understand the meaning of dividing integers with a remainder.

Dividing a negative integer a by a positive integer b can also be given meaning. To do this, consider a negative integer as debt. Let's imagine this situation. The debt that constitutes the items must be repaid by b people by making an equal contribution. The absolute value of the incomplete quotient c in this case will determine the amount of debt of each of these people, and the remainder d will show how many items will remain after the debt is paid. Let's give an example. Let's say 2 people owe 7 apples. If we assume that each of them owes 4 apples, then after paying the debt they will have 1 apple left. This situation corresponds to equality (−7):2=−4 (remaining 1).

We will not attach any meaning to division with a remainder of an arbitrary integer a by a negative integer, but we will reserve its right to exist.

Theorem on the divisibility of integers with remainder

When we talked about dividing natural numbers with a remainder, we found out that the dividend a, divisor b, partial quotient c and remainder d are related by the equality a=b·c+d. The integers a, b, c and d have the same relationship. This connection is confirmed as follows divisibility theorem with remainder.

Theorem.

Any integer a can be uniquely represented through an integer and non-zero number b in the form a=b·q+r, where q and r are some integers, and .

Proof.

First, we prove the possibility of representing a=b·q+r.

If integers a and b are such that a is divisible by b, then by definition there is an integer q such that a=b·q. In this case, the equality a=b·q+r at r=0 holds.

Now we will assume that b is a positive integer. Let us choose an integer q in such a way that the product b·q does not exceed the number a, and the product b·(q+1) is already greater than a. That is, we take q such that the inequalities b q

It remains to prove the possibility of representing a=b·q+r for negative b .

Since the modulus of the number b in this case is a positive number, then for there is a representation where q 1 is some integer, and r is an integer that satisfies the conditions. Then, taking q=−q 1, we obtain the required representation a=b·q+r for negative b.

Let's move on to the proof of uniqueness.

Suppose that in addition to the representation a=b·q+r, q and r are integers and , there is another representation a=b·q 1 +r 1, where q 1 and r 1 are some integers, and q 1 ≠ q and .

After subtracting the left and right sides of the second equality from the left and right sides of the first equality, respectively, we obtain 0=b·(q−q 1)+r−r 1, which is equivalent to the equality r−r 1 =b·(q 1 −q) . Then an equality of the form , and due to the properties of the modulus of numbers, the equality .

From the conditions we can conclude that. Since q and q 1 are integers and q≠q 1, then we conclude that . From the obtained inequalities and it follows that an equality of the form impossible under our assumption. Therefore, there is no other representation of the number a other than a=b·q+r.

Relationships between dividend, divisor, partial quotient and remainder

The equality a=b·c+d allows you to find the unknown dividend a if the divisor b, partial quotient c and remainder d are known. Let's look at an example.

Example.

What is the value of the dividend if, when divided by the integer −21, the result is an incomplete quotient of 5 and a remainder of 12?

Solution.

We need to calculate the dividend a when the divisor b=−21, the partial quotient c=5 and the remainder d=12 are known. Turning to the equality a=b·c+d, we obtain a=(−21)·5+12. Observing, we first multiply the integers −21 and 5 according to the rule for multiplying integers with different signs, after which we perform the addition of integers with different signs: (−21)·5+12=−105+12=−93.

Answer:

−93 .

The connections between the dividend, divisor, partial quotient and remainder are also expressed by equalities of the form b=(a−d):c, c=(a−d):b and d=a−b·c. These equalities allow you to calculate the divisor, partial quotient, and remainder, respectively. We will often have to find the remainder when dividing an integer a by an integer b when the dividend, divisor and partial quotient are known, using the formula d=a−b·c. To avoid any further questions, let’s look at an example of calculating the remainder.

Example.

Find the remainder when dividing the integer −19 by the integer 3 if you know that the partial quotient is equal to −7.

Solution.

To calculate the remainder of division, we use a formula of the form d=a−b·c. From the condition we have all the necessary data a=−19, b=3, c=−7. We get d=a−b·c=−19−3·(−7)= −19−(−21)=−19+21=2 (we calculated the difference −19−(−21) using the rule of subtracting a negative integer ).

Answer:

Division with remainder of positive integers, examples

As we have noted more than once, positive integers are natural numbers. Therefore, division with a remainder of positive integers is carried out according to all the rules for division with a remainder of natural numbers. It is very important to be able to easily perform division with a remainder of natural numbers, since it is this that underlies the division of not only positive integers, but also the basis of all rules for division with a remainder of arbitrary integers.

From our point of view, it is most convenient to perform column division; this method allows you to obtain both an incomplete quotient (or simply a quotient) and a remainder. Let's look at an example of division with a remainder of positive integers.

Example.

Divide with remainder 14,671 by 54.

Solution.

Let's divide these positive integers with a column:

The partial quotient turned out to be equal to 271, and the remainder is equal to 37.

Answer:

14 671:54=271 (rest. 37) .

The rule for dividing with a remainder a positive integer by a negative integer, examples

Let us formulate a rule that allows us to perform division with a remainder of a positive integer by a negative integer.

The partial quotient of dividing a positive integer a by a negative integer b is the opposite of the partial quotient of dividing a by the modulus of b, and the remainder of dividing a by b is equal to the remainder of dividing by.

From this rule it follows that the partial quotient of dividing a positive integer by a negative integer is a non-positive integer.

Let’s transform the stated rule into an algorithm for dividing with a remainder a positive integer by a negative integer:

  • We divide the modulus of the dividend by the modulus of the divisor, obtaining the partial quotient and remainder. (If the remainder is equal to zero, then the original numbers are divided without a remainder, and according to the rule for dividing integers with opposite signs, the required quotient is equal to the number opposite to the quotient from the division of the modules.)
  • We write down the number opposite to the resulting incomplete quotient and the remainder. These numbers are, respectively, the required quotient and the remainder of dividing the original positive integer by a negative integer.

Let's give an example of using the algorithm for dividing a positive integer by a negative integer.

Example.

Divide with a remainder of the positive integer 17 by the negative integer −5.

Solution.

Let's use the algorithm for dividing with a remainder a positive integer by a negative integer.

By dividing

The opposite number of 3 is −3. Thus, the required partial quotient of dividing 17 by −5 is −3, and the remainder is 2.

Answer:

17 :(−5)=−3 (remaining 2).

Example.

Divide 45 by −15.

Solution.

The modules of the dividend and divisor are 45 and 15, respectively. The number 45 is divisible by 15 without a remainder, and the quotient is 3. Therefore, the positive integer 45 is divided by the negative integer −15 without a remainder, and the quotient is equal to the number opposite 3, that is, −3. Indeed, according to the rule for dividing integers with different signs, we have .

Answer:

45:(−15)=−3 .

Division with remainder of a negative integer by a positive integer, examples

Let us give the formulation of the rule for dividing a negative integer with a remainder by a positive integer.

To obtain an incomplete quotient c from dividing a negative integer a by a positive integer b, you need to take the number opposite to the incomplete quotient from dividing the moduli of the original numbers and subtract one from it, after which the remainder d is calculated using the formula d=a−b·c.

From this rule of division with a remainder it follows that the partial quotient of dividing a negative integer by a positive integer is a negative integer.

From the stated rule follows an algorithm for dividing with a remainder a negative integer a by a positive integer b:

  • Finding the modules of the dividend and divisor.
  • We divide the modulus of the dividend by the modulus of the divisor, obtaining the partial quotient and remainder. (If the remainder is zero, then the original integers are divided without a remainder, and the required quotient is equal to the number opposite to the quotient of the modulus division.)
  • We write down the number opposite to the resulting incomplete quotient and subtract the number 1 from it. The calculated number is the desired partial quotient c from dividing the original negative integer by a positive integer.

Let's analyze the solution to the example, in which we use the written division algorithm with a remainder.

Example.

Find the partial quotient and remainder when dividing the negative integer −17 by the positive integer 5.

Solution.

The modulus of the dividend −17 is equal to 17, and the modulus of the divisor 5 is equal to 5.

By dividing 17 by 5, we get the partial quotient 3 and the remainder 2.

The opposite of 3 is −3. Subtract one from −3: −3−1=−4. So, the required partial quotient is equal to −4.

All that remains is to calculate the remainder. In our example a=−17 , b=5 , c=−4 , then d=a−b·c=−17−5·(−4)= −17−(−20)=−17+20=3 .

Thus, the partial quotient of dividing the negative integer −17 by the positive integer 5 is −4, and the remainder is 3.

Answer:

(−17):5=−4 (remaining 3) .

Example.

Divide the negative integer −1,404 by the positive integer 26.

Solution.

The module of the dividend is 1,404, the module of the divisor is 26.

Divide 1,404 by 26 using a column:

Since the module of the dividend is divided by the module of the divisor without a remainder, the original integers are divided without a remainder, and the desired quotient is equal to the number opposite 54, that is, −54.

Answer:

(−1 404):26=−54 .

Division rule with remainder for negative integers, examples

Let us formulate the rule for division with a remainder of negative integers.

To obtain an incomplete quotient c from dividing a negative integer a by a negative integer b, you need to calculate the incomplete quotient from dividing the moduli of the original numbers and add one to it, after which the remainder d is calculated using the formula d=a−b·c.

From this rule it follows that the partial quotient of dividing negative integers is a positive integer.

Let's rewrite the stated rule in the form of an algorithm for dividing negative integers:

  • Finding the modules of the dividend and divisor.
  • We divide the modulus of the dividend by the modulus of the divisor, obtaining the partial quotient and remainder. (If the remainder is zero, then the original integers are divided without a remainder, and the required quotient is equal to the quotient of the modulus of the divisor divided by the modulus of the divisor.)
  • We add one to the resulting incomplete quotient; this number is the desired incomplete quotient from the division of the original negative integers.
  • We calculate the remainder using the formula d=a−b·c.

Let's consider the use of the algorithm for dividing negative integers when solving an example.

Example.

Find the partial quotient and remainder when dividing a negative integer −17 by a negative integer −5.

Solution.

Let's use the appropriate division algorithm with a remainder.

The module of the dividend is 17, the module of the divisor is 5.

Division 17 over 5 gives the partial quotient 3 and the remainder 2.

To the incomplete quotient 3 we add one: 3+1=4. Therefore, the required partial quotient of dividing −17 by −5 is equal to 4.

All that remains is to calculate the remainder. In this example a=−17 , b=−5 , c=4 , then d=a−b·c=−17−(−5)·4= −17−(−20)=−17+20=3 .

So, the partial quotient of dividing a negative integer −17 by a negative integer −5 is 4, and the remainder is 3.

Answer:

(−17):(−5)=4 (remaining 3) .

Checking the result of dividing integers with a remainder

After dividing integers with a remainder, it is useful to check the result. The verification is carried out in two stages. At the first stage, it is checked whether the remainder d is a non-negative number, and the condition is also checked. If all the conditions of the first stage of verification are met, then you can proceed to the second stage of verification, otherwise it can be argued that an error was made somewhere when dividing with a remainder. At the second stage, the validity of the equality a=b·c+d is checked. If this equality is true, then the division with a remainder was carried out correctly, otherwise an error was made somewhere.

Let's look at solutions to examples in which the result of dividing integers with a remainder is checked.

Example.

When dividing the number −521 by −12, the partial quotient was 44 and the remainder was 7, check the result.

Solution. −2 for b=−3, c=7, d=1. We have b c+d=−3·7+1=−21+1=−20. Thus, the equality a=b·c+d is incorrect (in our example a=−19).

Therefore, division with a remainder was carried out incorrectly.