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Subtraction of Whole Numbers

Module by: Wade Ellis, Denny Burzynski. E-mail the authorsEdited By: Math Editors

Summary: This module is from Fundamentals of Mathematics by Denny Burzynski and Wade Ellis, Jr. This module discusses how to subtract whole numbers. By the end of this module, students should be able to understand the subtraction process, subtract whole numbers, and use a calculator to subtract one whole number from another whole number.

Section Overview

  • Subtraction
  • Subtraction as the Opposite of Addition
  • The Subtraction Process
  • Subtraction Involving Borrowing
  • Borrowing From Zero
  • Calculators

Subtraction

Subtraction

Subtraction is the process of determining the remainder when part of the total is removed.

Suppose the sum of two whole numbers is 11, and from 11 we remove 4. Using the number line to help our visualization, we see that if we are located at 11 and move 4 units to the left, and thus remove 4 units, we will be located at 7. Thus, 7 units remain when we remove 4 units from 11 units.

A number line, with an arrow, labeled -4, drawn from the mark for 11 to the mark for 7.

The Minus Symbol

The minus symbol (-) is used to indicate subtraction. For example, 114114 size 12{"11" - 4} {} indicates that 4 is to be subtracted from 11.

Minuend

The number immediately in front of or the minus symbol is called the minuend, and it represents the original number of units.

Subtrahend

The number immediately following or below the minus symbol is called the subtrahend, and it represents the number of units to be removed.

Difference

The result of the subtraction is called the difference of the two numbers. For example, in 114=7114=7 size 12{"11" - 4=7} {}, 11 is the minuend, 4 is the subtrahend, and 7 is the difference.

Subtraction as the Opposite of Addition

Subtraction can be thought of as the opposite of addition. We show this in the problems in Sample Set A.

Sample Set A

Example 1

85=385=3 size 12{8 - 5=3} {} since 3+5=83+5=8 size 12{3+5=8} {}.

Example 2

93=693=6 size 12{9 - 3=6} {} since 6+3=96+3=9 size 12{6+3=9} {}.

Practice Set A

Complete the following statements.

Exercise 1

75=75= size 12{7 - 5={}} {}

          
since
          
+5=7+5=7 size 12{+5=7} {}.

Solution

7-5=27-5=2 since 2+5=72+5=7

Exercise 2

91=91= size 12{9 - 1={}} {}

          
since
          
+1=9+1=9 size 12{+1=9} {}.

Solution

9-1=89-1=8 since 8+1=98+1=9

Exercise 3

178=178= size 12{"17" - 8={}} {}

          
since
          
+8=17+8=17 size 12{+8="17"} {}.

Solution

17-8=917-8=9 since 9+8=179+8=17

The Subtraction Process

We'll study the process of the subtraction of two whole numbers by considering the difference between 48 and 35.

Vertical subtraction. 48 - 35 means, 4 tens + 8 ones, minus 3 tens - 5 ones = 1 ten + 3 ones.

which we write as 13.

Example 3: The Process of Subtracting Whole Numbers

To subtract two whole numbers,

The process

  1. Write the numbers vertically, placing corresponding positions in the same column.

    48 - 35 ̲ 48 - 35 ̲

  2. Subtract the digits in each column. Start at the right, in the ones position, and move to the left, placing the difference at the bottom.

    48 - 35 ̲ 13 48 - 35 ̲ 13

Sample Set B

Perform the following subtractions.

Example 4

275 - 142 ̲ 133 275 - 142 ̲ 133

5 2 = 3 . 7 4 = 3 . 2 1 = 1 . 5 2 = 3 . 7 4 = 3 . 2 1 = 1 . alignr { stack { size 12{5 - 2=3 "." } {} # size 12{7 - 4=3 "." } {} # size 12{2 - 1=1 "." } {} } } {}

Example 5

46,042 -   1,031 ̲ 45,011 46,042 -   1,031 ̲ 45,011

2 1 = 1 . 4 3 = 1 . 0 0 = 0 . 6 1 = 5 . 4 0 = 4 . 2 1 = 1 . 4 3 = 1 . 0 0 = 0 . 6 1 = 5 . 4 0 = 4 . alignr { stack { size 12{2 - 1=1 "." } {} # size 12{4 - 3=1 "." } {} # size 12{0 - 0=0 "." } {} # size 12{6 - 1=5 "." } {} # size 12{4 - 0=4 "." } {} } } {}

Example 6

Find the difference between 977 and 235.

Write the numbers vertically, placing the larger number on top. Line up the columns properly.

977 - 235 ̲ 742 977 - 235 ̲ 742

The difference between 977 and 235 is 742.

Example 7

In Keys County in 1987, there were 809 cable television installations. In Flags County in 1987, there were 1,159 cable television installations. How many more cable television installations were there in Flags County than in Keys County in 1987?

We need to determine the difference between 1,159 and 809.

1,159 - 809 = 350, with a 1 above the thousands and hundreds columns.

There were 350 more cable television installations in Flags County than in Keys County in 1987.

Practice Set B

Perform the following subtractions.

Exercise 4

534 - 203 ̲ 534 - 203 ̲

Solution

331

Exercise 5

857 -   43 ̲ 857 -   43 ̲

Solution

814

Exercise 6

95,628 - 34,510 ̲ 95,628 - 34,510 ̲

Solution

61,118

Exercise 7

11,005 -   1,005 ̲ 11,005 -   1,005 ̲

Solution

10,000

Exercise 8

Find the difference between 88,526 and 26,412.

Solution

62,114

In each of these problems, each bottom digit is less than the corresponding top digit. This may not always be the case. We will examine the case where the bottom digit is greater than the corresponding top digit in the next section.

Subtraction Involving Borrowing

Minuend and Subtrahend

It often happens in the subtraction of two whole numbers that a digit in the minuend (top number) will be less than the digit in the same position in the subtrahend (bottom number). This happens when we subtract 27 from 84.

84 - 27 ̲ 84 - 27 ̲

We do not have a name for 4747 size 12{4 - 7} {}. We need to rename 84 in order to continue. We'll do so as follows:

Vertical subtraction. 84 - 27 is equal to 8 tens + 4 ones, over 2 tens + 7 ones.

Vertical subtraction. 7 tens + 1 ten + 4 ones, over 2 tens + 7 ones.

Vertical subtraction. 7 tens + 10 ones + 4 ones, over 2 tens + 7 ones.

Our new name for 84 is 7 tens + 14 ones.

Vertical subtraction. 7 tens + 14 ones, over 2 tens + 7 ones = 5 tens + 7 ones.
= 57 = 57

Notice that we converted 8 tens to 7 tens + 1 ten, and then we converted the 1 ten to 10 ones. We then had 14 ones and were able to perform the subtraction.

Borrowing

The process of borrowing (converting) is illustrated in the problems of Sample Set C.

Sample Set C

Example 8

84 - 27 = 57. The 8 in 84 is crossed out, with a 7 above it. There is a 14 above the ones column.

  1. Borrow 1 ten from the 8 tens. This leaves 7 tens.
  2. Convert the 1 ten to 10 ones.
  3. Add 10 ones to 4 ones to get 14 ones.

Example 9

672 - 91 = 581. The 6 in 672 is crossed out, with a 5 above it. The 7 in 672 is crossed out, with 17 above it.

  1. Borrow 1 hundred from the 6 hundreds. This leaves 5 hundreds.
  2. Convert the 1 hundred to 10 tens.
  3. Add 10 tens to 7 tens to get 17 tens.

Practice Set C

Perform the following subtractions. Show the expanded form for the first three problems.

Exercise 9

53 - 35 ̲ 53 - 35 ̲

Solution

The solution is 18. The subtraction can be broken into the quantity 5 tens + 3 ones, minus  the quantity 3 tens + 5 ones. 5 tens + 3 ones can be broken down to 4 tens + 1 ten + 3 ones, or 4 tens + 13 ones. The difference is 1 ten + 8 ones, or 18.

Exercise 10

76 - 28 ̲ 76 - 28 ̲

Solution

The solution is 48. The subtraction problem can be expanded to the quantity 7 tens + 6 ones, minus the quantity 2 tens + 8 ones. 7 tens + 6 ones can be expanded to be 6 tens + 1 ten + 6 ones, or 6 tens + 16 ones. The sum becomes 4 tens + 8 ones, or 48.

Exercise 11

872 - 565 ̲ 872 - 565 ̲

Solution

The solution is 307. The subtraction problem can be expanded to be the quantity, 8 hundreds + 7 tens + 2 ones, minus the quantity, 5 hundreds + 6 tens + 5 ones. 8 hundreds + 7 tens + 2 ones can be expanded to 8 hundreds + 6 tens + 1 ten + 2 ones, or 8 hundreds + 6 tens + 12 ones. The difference is 3 hundreds + 0 tens + 7 ones, or 307.

Exercise 12

441 - 356 ̲ 441 - 356 ̲

Solution

85

Exercise 13

775 -   66 ̲ 775 -   66 ̲

Solution

709

Exercise 14

5,663 - 2,559 ̲ 5,663 - 2,559 ̲

Solution

3,104

Borrowing More Than Once

Sometimes it is necessary to borrow more than once. This is shown in the problems in Section 12.

Sample Set D

Perform the Subtractions. Borrowing more than once if necessary

Example 10

641 - 358 = 283. the 4 in 641 is crossed out, with a 3 marked above it. Above the 1 in 641 is 11. The 6 in 641 is then crossed out, with a 5 marked above it. The 3 above the 4 is crossed out, with a 13 marked above it.

  1. Borrow 1 ten from the 4 tens. This leaves 3 tens.
  2. Convert the 1 ten to 10 ones.
  3. Add 10 ones to 1 one to get 11 ones. We can now perform 118118 size 12{"11" - 8} {}.
  4. Borrow 1 hundred from the 6 hundreds. This leaves 5 hundreds.
  5. Convert the 1 hundred to 10 tens.
  6. Add 10 tens to 3 tens to get 13 tens.
  7. Now 135=8135=8 size 12{"13" - 5=8} {}.
  8. 53=253=2 size 12{5 - 3=2} {}.

Example 11

534 - 85 = 449. The 3 in 534 is crossed out, with a 2 above it. Above the 4 is a 14. The 5 in 534 is then crossed out, with a 4 marked above it. The 2 above the 3 in 534 is crossed out, with a 12 above it.

  1. Borrow 1 ten from the 3 tens. This leaves 2 tens.
  2. Convert the 1 ten to 10 ones.
  3. Add 10 ones to 4 ones to get 14 ones. We can now perform 145145 size 12{"14" - 5} {}.
  4. Borrow 1 hundred from the 5 hundreds. This leaves 4 hundreds.
  5. Convert the 1 hundred to 10 tens.
  6. Add 10 tens to 2 tens to get 12 tens. We can now perform 128=4128=4 size 12{"12" - 8=4} {}.
  7. Finally, 40=440=4 size 12{4 - 0=4} {}.

Example 12

71529 - 6952 ̲ 71529 - 6952 ̲ alignr { stack { size 12{"71529"} {} # size 12{ {underline { - "6952"}} } {} } } {}

After borrowing, we have

71529 - 6952 = 64577. Above the 5 is a 4, and above the 2 is a 12.  Above the 1 is a 0, and above the 7 is a 6. The 0 and the 4 are crossed out, with a 14 written above the 4, and a 10 written above the 0.

Practice Set D

Perform the following subtractions.

Exercise 15

526 - 358 ̲ 526 - 358 ̲

Solution

168

Exercise 16

63,419 -   7,779 ̲ 63,419 -   7,779 ̲

Solution

55,640

Exercise 17

4,312 - 3,123 ̲ 4,312 - 3,123 ̲

Solution

1,189

Borrowing from Zero

It often happens in a subtraction problem that we have to borrow from one or more zeros. This occurs in problems such as

  1. 503 -   37 ̲ 503 -   37 ̲

    and
  2. 5000 -     37 ̲ 5000 -     37 ̲

We'll examine each case.

Example 13: Borrowing from a single zero.

Consider the problem 503 -   37 ̲ 503 -   37 ̲

Since we do not have a name for 3737 size 12{3 - 7} {}, we must borrow from 0.

Vertical subtraction. 503 - 37 is equal to 5 hundreds + 0 tens + 3 ones, minus 3 tens + 7 ones.

Since there are no tens to borrow, we must borrow 1 hundred. One hundred = 10 tens.

Vertical subtraction. 4 hundreds + 10 tens + 3 ones, minus 3 tens + 7 ones.

We can now borrow 1 ten from 10 tens (leaving 9 tens). One ten = 10 ones and 10 ones + 3 ones = 13 ones.

Vertical subtraction. 4 hundreds + 9 tens + 13 ones, minus 3 tens + 7 ones = 4 hundreds + 6 tens + 6 ones, equal to 466.

Now we can suggest the following method for borrowing from a single zero.

Borrowing from a Single Zero

To borrow from a single zero,

  1. Decrease the digit to the immediate left of zero by one.
  2. Draw a line through the zero and make it a 10.
  3. Proceed to subtract as usual.

Sample Set E

Example 14

Perform this subtraction.

503 -   37 ̲ 503 -   37 ̲

The number 503 contains a single zero

  1. The number to the immediate left of 0 is 5. Decrease 5 by 1.

    5 1 = 4 5 1 = 4 size 12{5 - 1=4} {}

    503 - 37. The 5 is crossed out, with a 4 above it. The 0 is crossed out, with a 10 above it.

  2. Draw a line through the zero and make it a 10.
  3. Borrow from the 10 and proceed.

    503 - 37. The 5 is crossed out, with a 4 above it. The 0 is crossed out, with a 10 above it. The 10 is crossed out, with a 9 above it. The 3 is crossed out, with a 13 above it. The difference is 466.

    1 ten+10 ones1 ten+10 ones

    10 ones+ 3 ones=13 ones10 ones+3 ones=13 ones

Practice Set E

Perform each subtraction.

Exercise 18

906 -   18 ̲ 906 -   18 ̲

Solution

888

Exercise 19

5102 -   559 ̲ 5102 -   559 ̲

Solution

4,543

Exercise 20

9055 -   386 ̲ 9055 -   386 ̲

Solution

8,669

Example 15: Borrowing from a group of zeros

Consider the problem 5000 -     37 ̲ 5000 -     37 ̲

In this case, we have a group of zeros.

Vertical subtraction. 5000 - 37 is equal to 5 thousands + 0 hundred + 0 tens + 0 ones, minus 3 tens + 7 ones.

Since we cannot borrow any tens or hundreds, we must borrow 1 thousand. One thousand = 10 hundreds.

Vertical subtraction. 4 thousands + 10 hundreds + 0 tens + 0 ones, minus 3 tens + 7 ones.

We can now borrow 1 hundred from 10 hundreds. One hundred = 10 tens.

Vertical subtraction. 4 thousands + 9 hundreds + 10 tens + 0 ones, minus 3 tens + 7 ones.

We can now borrow 1 ten from 10 tens. One ten = 10 ones.

Vertical subtraction. 4 thousands + 9 hundreds + 9 tens + 10 ones, minus 3 tens + 7 ones = 4 thousands + 9 hundreds + 6 tens + 3 ones, equal to 4,963

From observations made in this procedure we can suggest the following method for borrowing from a group of zeros.

Borrowing from a Group of zeros

To borrow from a group of zeros,

  1. Decrease the digit to the immediate left of the group of zeros by one.
  2. Draw a line through each zero in the group and make it a 9, except the rightmost zero, make it 10.
  3. Proceed to subtract as usual.

Sample Set F

Perform each subtraction.

Example 16

40,000 -     125 ̲ 40,000 -     125 ̲

The number 40,000 contains a group of zeros.

  1. The number to the immediate left of the group is 4. Decrease 4 by 1.

    4 1 = 3 4 1 = 3 size 12{4 - 1=3} {}

  2. Make each 0, except the rightmost one, 9. Make the rightmost 0 a 10.

    40,000 - 125. Each digit of 40,000 is crossed out, and above it from left to right are the numbers, 3, 9, 9, 9, and 10.

  3. Subtract as usual.

    40,000 - 125. Each digit of 40,000 is crossed out, and above it from left to right are the numbers, 3, 9, 9, 9, and 10. The difference is 39,875.

Example 17

8,000,006 -       41,107 ̲ 8,000,006 -       41,107 ̲

The number 8,000,006 contains a group of zeros.

  1. The number to the immediate left of the group is 8. Decrease 8 by 1.

    8 1 = 7 8 1 = 7 size 12{8 - 1=7} {}

  2. Make each zero, except the rightmost one, 9. Make the rightmost 0 a 10.

    8,000,006 - 41,107. All but the ones digit are crossed out, and above them from left to right are 7, 9, 9, 9, 9, and 10.

  3. To perform the subtraction, we’ll need to borrow from the ten.

    8,000,006 - 41,107. All but the ones digit are crossed out, and above them from left to right are 7, 9, 9, 9, 9, and 10. The 10 is crossed out, with a 9 above it. Above the 6 is a 16. The difference is 7,958,899.


    1 ten = 10 ones 10 ones + 6 ones = 16 ones 1 ten = 10 ones 10 ones + 6 ones = 16 ones

Practice Set F

Perform each subtraction.

Exercise 21

21,007 -   4,873 ̲ 21,007 -   4,873 ̲

Solution

16,134

Exercise 22

10,004 -   5,165 ̲ 10,004 -   5,165 ̲

Solution

4,839

Exercise 23

16,000,000 -      201,060 ̲ 16,000,000 -      201,060 ̲

Solution

15,789,940

Calculators

In practice, calculators are used to find the difference between two whole numbers.

Sample Set G

Find the difference between 1006 and 284.

Table 1
Display Reads
Type 1006 1006
Press size 12{` - `} {} 1006
Type 284 284
Press = 722

The difference between 1006 and 284 is 722.

(What happens if you type 284 first and then 1006? We'll study such numbers in (Reference)Chapter 10.)

Practice Set G

Exercise 24

Use a calculator to find the difference between 7338 and 2809.

Solution

4,529

Exercise 25

Use a calculator to find the difference between 31,060,001 and 8,591,774.

Solution

22,468,227

Exercises

For the following problems, perform the subtractions. You may check each difference with a calculator.

Exercise 26

15 -   8 ̲ 15 -   8 ̲

Solution

7

Exercise 27

19 -   8 ̲ 19 -   8 ̲

Exercise 28

11 -   5 ̲ 11 -   5 ̲

Solution

6

Exercise 29

14 -   6 ̲ 14 -   6 ̲

Exercise 30

12 -   9 ̲ 12 -   9 ̲

Solution

3

Exercise 31

56 - 12 ̲ 56 - 12 ̲

Exercise 32

74 - 33 ̲ 74 - 33 ̲

Solution

41

Exercise 33

80 - 61 ̲ 80 - 61 ̲

Exercise 34

350 - 141 ̲ 350 - 141 ̲

Solution

209

Exercise 35

800 - 650 ̲ 800 - 650 ̲

Exercise 36

35,002 - 14,001 ̲ 35,002 - 14,001 ̲

Solution

21,001

Exercise 37

5,000,566 - 2,441,326 ̲ 5,000,566 - 2,441,326 ̲

Exercise 38

400,605 - 121,352 ̲ 400,605 - 121,352 ̲

Solution

279,253

Exercise 39

46,400 -   2,012 ̲ 46,400 -   2,012 ̲

Exercise 40

77,893 -      421 ̲ 77,893 -      421 ̲

Solution

77,472

Exercise 41

42 - 18 ̲ 42 - 18 ̲

Exercise 42

51 - 27 ̲ 51 - 27 ̲

Solution

24

Exercise 43

622 -   88 ̲ 622 -   88 ̲

Exercise 44

261 -   73 ̲ 261 -   73 ̲

Solution

188

Exercise 45

242 - 158 ̲ 242 - 158 ̲

Exercise 46

3,422 - 1,045 ̲ 3,422 - 1,045 ̲

Solution

2,377

Exercise 47

5,565 - 3,985 ̲ 5,565 - 3,985 ̲

Exercise 48

42,041 - 15,355 ̲ 42,041 - 15,355 ̲

Solution

26,686

Exercise 49

304,056 -   20,008 ̲ 304,056 -   20,008 ̲

Exercise 50

64,000,002 -     856,743 ̲ 64,000,002 -     856,743 ̲

Solution

63,143,259

Exercise 51

4,109 -   856 ̲ 4,109 -   856 ̲

Exercise 52

10,113 -   2,079 ̲ 10,113 -   2,079 ̲

Solution

8,034

Exercise 53

605 -   77 ̲ 605 -   77 ̲

Exercise 54

59 - 26 ̲ 59 - 26 ̲

Solution

33

Exercise 55

36,107 -   8,314 ̲ 36,107 -   8,314 ̲

Exercise 56

92,526,441,820 - 59,914,805,253 ̲ 92,526,441,820 - 59,914,805,253 ̲

Solution

32,611,636,567

Exercise 57

1,605 -   881 ̲ 1,605 -   881 ̲

Exercise 58

30,000 - 26,062 ̲ 30,000 - 26,062 ̲

Solution

3,938

Exercise 59

600 - 216 ̲ 600 - 216 ̲

Exercise 60

9,000,003 -    726,048 ̲ 9,000,003 -    726,048 ̲

Solution

8,273,955

For the following problems, perform each subtraction.

Exercise 61

Subtract 63 from 92.

Hint:

The word "from" means "beginning at." Thus, 63 from 92 means beginning at 92, or 92 63 92 63 size 12{"92" - "63"} {} .

Exercise 62

Subtract 35 from 86.

Solution

51

Exercise 63

Subtract 382 from 541.

Exercise 64

Subtract 1,841 from 5,246.

Solution

3,405

Exercise 65

Subtract 26,082 from 35,040.

Exercise 66

Find the difference between 47 and 21.

Solution

26

Exercise 67

Find the difference between 1,005 and 314.

Exercise 68

Find the difference between 72,085 and 16.

Solution

72,069

Exercise 69

Find the difference between 7,214 and 2,049.

Exercise 70

Find the difference between 56,108 and 52,911.

Solution

3,197

Exercise 71

How much bigger is 92 than 47?

Exercise 72

How much bigger is 114 than 85?

Solution

29

Exercise 73

How much bigger is 3,006 than 1,918?

Exercise 74

How much bigger is 11,201 than 816?

Solution

10,385

Exercise 75

How much bigger is 3,080,020 than 1,814,161?

Exercise 76

In Wichita, Kansas, the sun shines about 74% of the time in July and about 59% of the time in November. How much more of the time (in per­cent) does the sun shine in July than in No­vember?

Solution

15%

Exercise 77

The lowest temperature on record in Concord, New Hampshire in May is 21°F, and in July it is 35°F. What is the difference in these lowest tem­peratures?

Exercise 78

In 1980, there were 83,000 people arrested for prostitution and commercialized vice and 11,330,000 people arrested for driving while in­toxicated. How many more people were arrested for drunk driving than for prostitution?

Solution

11,247,000

Exercise 79

In 1980, a person with a bachelor's degree in ac­counting received a monthly salary offer of $1,293, and a person with a marketing degree a monthly salary offer of $1,145. How much more was offered to the person with an accounting de­gree than the person with a marketing degree?

Exercise 80

In 1970, there were about 793 people per square mile living in Puerto Rico, and 357 people per square mile living in Guam. How many more people per square mile were there in Puerto Rico than Guam?

Solution

436

Exercise 81

The 1980 population of Singapore was 2,414,000 and the 1980 population of Sri Lanka was 14,850,000. How many more people lived in Sri Lanka than in Singapore in 1980?

Exercise 82

In 1977, there were 7,234,000 hospitals in the United States and 64,421,000 in Mainland China. How many more hospitals were there in Mainland China than in the United States in 1977?

Solution

57,187,000

Exercise 83

In 1978, there were 3,095,000 telephones in use in Poland and 4,292,000 in Switzerland. How many more telephones were in use in Switzerland than in Poland in 1978?

For the following problems, use the corresponding graphs to solve the problems.

Exercise 84

How many more life scientists were there in 1974 than mathematicians? (Media 29)

Solution

165,000

Exercise 85

How many more social, psychological, mathe­matical, and environmental scientists were there than life, physical, and computer scientists? (Media 29)

A graph entitled employment status of mathematical scientists - 1974. On the graph are histograms with scientific field titles, and a labeled number of the scientists holding the titles. There are 266,000 life scientists, 248,000 physical scientists, 170,000 computer scientists, 217,000 social scientists, 109,000 psychologists, 101,000, mathematicians, and 79,000 environmental scientists.

Exercise 86

How many more prosecutions were there in 1978 than in 1974? (Media 30)

Solution

74

Exercise 87

How many more prosecutions were there in 1976-1980 than in 1970-1975? (Media 30)

A graph entitled prosecutions of federal officials 1970-1980, with histograms of the years on the horizontal axis, and number of prosecutions on the vertical axis. The years in ascending succession had the following number of prosecutions, 9, 58, 58, 60, 59, 53, 111, 129, 133, 114, 123.

Exercise 88

How many more dry holes were drilled in 1960 than in 1975? (Media 31)

Solution

4,547

Exercise 89

How many more dry holes were drilled in 1960, 1965, and 1970 than in 1975, 1978 and 1979? (Media 31)

A graph entitled, oil wells -  dry holes drilled 1960-1979. The histograms of the years in the period are displayed along the horizontal axis. The number of holes are measured on the vertical axis. The number of holes drilled, for each consecutive year 1960, 1965, 1970, 1975, 1978, and 1979, are 17,577, 15,967, 10,786, 13,030, 15,559, 15,201.

For the following problems, replace the ☐ with the whole number that will make the subtraction true.

Exercise 90

14 - ̲ 3 14 - ̲ 3

Solution

11

Exercise 91

21 - ̲ 14 21 - ̲ 14

Exercise 92

35 - ̲ 25 35 - ̲ 25

Solution

10

Exercise 93

16 - ̲ 9 16 - ̲ 9

Exercise 94

28 - ̲ 16 28 - ̲ 16

Solution

12

For the following problems, find the solutions.

Exercise 95

Subtract 42 from the sum of 16 and 56.

Exercise 96

Subtract 105 from the sum of 92 and 89.

Solution

76

Exercise 97

Subtract 1,127 from the sum of 2,161 and 387.

Exercise 98

Subtract 37 from the difference between 263 and 175.

Solution

51

Exercise 99

Subtract 1,109 from the difference between 3,046 and 920.

Exercise 100

Add the difference between 63 and 47 to the dif­ference between 55 and 11.

Solution

60

Exercise 101

Add the difference between 815 and 298 to the difference between 2,204 and 1,016.

Exercise 102

Subtract the difference between 78 and 43 from the sum of 111 and 89.

Solution

165

Exercise 103

Subtract the difference between 18 and 7 from the sum of the differences between 42 and 13, and 81 and 16.

Exercise 104

Find the difference between the differences of 343 and 96, and 521 and 488.

Solution

214

Exercises for Review

Exercise 105

((Reference)) In the number 21,206, how many hundreds are there?

Exercise 106

((Reference)) Write a three-digit number that has a zero in the ones position.

Solution

330 (answers may vary)

Exercise 107

((Reference)) How many three-digit whole numbers are there?

Exercise 108

((Reference)) Round 26,524,016 to the nearest million.

Solution

27,000,000

Exercise 109

((Reference)) Find the sum of 846+221+116846+221+116 size 12{"846"+"221"+"116"} {}.

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