MENTAL MATH ADDITION WORKSHEET

In each case, evaluate the expression.

Problem 1 :

17 + 5

Problem 2 :

28 + 9

Problem 3 :

27 + 12

Problem 4 :

56 + 47

Problem 5 :

38 + 76

Problem 6 :

42 + 79

Problem 7 :

99 + 45

Problem 8 :

58 + 19

Problem 9 :

148 + 7

Problem 10 :

256 + 9

Problem 11 :

128 + 36

Problem 12 :

278 + 39

Problem 13 :

185 + 78

Problem 14 :

286 + 170

Problem 15 :

256 + 225

Problem 16 :

389 + 496

Problem 17 :

498 + 502

Problem 18 :

606 + 707

Problem 19 :

652 + 348

Problem 20 :

998 + 1005

Answers

1. Answer :

= 17 + 5

= 22

2. Answer :

= 28 + 9

= 37

3. Answer :

= 27 + 12

= 27 + 10 + 2

= 37 + 2

= 39

4. Answer :

= 56 + 47

= 56 + 40 + 7

= 96 + 7

= 103

5. Answer :

= 38 + 76

= 38 + 70 + 6

= 108 + 6

= 114

6. Answer :

= 42 + 79

= 42 + 80 - 1

= 122 - 1

= 123

7. Answer :

= 99 + 45

= 100 - 1 + 45

= 145 - 1

= 144

8. Answer :

= 58 + 19

= 60 - 2 + 19

= 79 - 2

= 77

9. Answer :

= 148 + 7

= 141

10. Answer :

= 256 + 9

= 247

11. Answer :

= 128 + 36

= 128 + 30 + 6

= 158 + 6

= 164

12. Answer :

= 278 + 39

= 278 + 40 - 1

= 318 - 1

= 317

13. Answer :

= 185 + 78

= 185 + 80 - 2

= 265 - 2

= 263

14. Answer :

= 286 + 170

= (200 + 100) + (86 + 70)

= 300 + 156

= 456

15. Answer :

= 256 + 225

= (200 + 200) + (56 + 25)

= 400 + 81

= 481

16. Answer :

= 389 + 496

= (400 + 500) + (-11 - 4)

= 900 - 15

= 885

17. Answer :

= 498 + 502

= (500 + 500) + (-2 + 2)

= 1000 + 0

= 1000 

18. Answer :

= 606 + 707

= (600 + 700) + (6 + 7)

= 1300 + 13

= 1313

19. Answer :

= 652 + 348

= (650 + 350) + (2 - 2)

= 1000 + 0

= 1000

20. Answer :

= 998 + 1005

= (1000 + 1000) + (-2 + 5)

= 2000 + 3

= 2003

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