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Adding 9, 19 and 99 Mental Maths Worksheet

Mental maths lesson 4: Add and take away 9, 19 and 99 · Set 561 · 40 questions
TalentJR

How to do it in your head (Round and adjust): Add 9, 19, 99: add 10, 20, 100, then take 1 away. Take away 9, 19, 99: take away 10, 20, 100, then add 1 back. Ask yourself: did I use too much or too little?

NameDateTime takenScore ___ / 40
  1. 1.72 + 29 =
  2. 2.56 − 9 =
  3. 3.13 + 9 =
  4. 4.72 − 29 =
  5. 5.28 + 19 =
  6. 6.55 + 9 =
  7. 7.40 + 9 =
  8. 8.25 + 29 =
  9. 9.26 + 19 =
  10. 10.49 + 29 =
  11. 11.51 − 9 =
  12. 12.69 − 29 =
  13. 13.35 − 29 =
  14. 14.59 + 19 =
  15. 15.48 + 29 =
  16. 16.17 + 19 =
  17. 17.109 − 29 =
  18. 18.13 + 29 =
  19. 19.302 + 99 =
  20. 20.72 − 9 =
  21. 21.67 + 9 =
  22. 22.94 − 29 =
  23. 23.208 − 99 =
  24. 24.768 − 99 =
  25. 25.575 + 99 =
  26. 26.247 − 99 =
  27. 27.18 + 29 =
  28. 28.433 − 99 =
  29. 29.17 + 9 =
  30. 30.12 + 9 =
  31. 31.18 + 19 =
  32. 32.61 + 19 =
  33. 33.381 − 99 =
  34. 34.51 + 9 =
  35. 35.732 + 99 =
  36. 36.43 + 9 =
  37. 37.39 + 19 =
  38. 38.69 − 9 =
  39. 39.538 + 99 =
  40. 40.12 + 29 =

Answer key

  1. 101
  2. 47
  3. 22
  4. 43
  5. 47
  6. 64
  7. 49
  8. 54
  9. 45
  10. 78
  11. 42
  12. 40
  13. 6
  14. 78
  15. 77
  16. 36
  17. 80
  18. 42
  19. 401
  20. 63
  21. 76
  22. 65
  23. 109
  24. 669
  25. 674
  26. 148
  27. 47
  28. 334
  29. 26
  30. 21
  31. 37
  32. 80
  33. 282
  34. 60
  35. 831
  36. 52
  37. 58
  38. 60
  39. 637
  40. 41

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