6th Grade Math Textbook, Progress

7

Operations III

Inverse Operations: Addition and Subtraction

Inverse operations are mathematical

operations that undoeach other.

Addition and subtraction are inverse operations.

Let a, b,and cbe any numbers.

If a
bc, then cba. If cba, then a
bc.

Subtraction “undoes” addition. Addition “undoes” subtraction.

Find the missing number.

x
 5  12

x 12  5

x 7

Think

7 
 5 12 and

12  5 7 are

related sentences.

Find the missing number.

x 9  15

x 15 
 9

x 24

Think

24  9 15 and

15 
 9 24 are

related sentences.

Multiplication and division are also inverse operations.

Let a, b,and cbe any numbers.

If abc, then cba. If cba, then abc.

Division “undoes” multiplication. Multiplication “undoes” division.

Find the missing number.

y 4  12

y 12  4

y 3

Think

3  4 12 and

12  4 3 are

related sentences.

Find the missing number.

y 6  18

y 18  6

y 108

Think

108  6 18 and

18  6 108 are

related sentences.

Find the missing number using inverse operations.

1. 8
   a 12 2. 36 b 9 3. r
   $2.96$10.00


2. n 40  56 5. 19 d 418 6. y 3  233


3. 45 a 675 8. 23 c$115.00 9. e
   468  9921


4. 99,999f 9898 11. g 321  123 12. $101.00 2 h

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