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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 160 · 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. 1.41 + 29 =
  2. 2.885 − 99 =
  3. 3.52 − 29 =
  4. 4.25 + 29 =
  5. 5.77 − 9 =
  6. 6.482 + 99 =
  7. 7.218 + 99 =
  8. 8.43 + 9 =
  9. 9.56 + 29 =
  10. 10.164 − 99 =
  11. 11.37 + 19 =
  12. 12.14 + 29 =
  13. 13.74 − 9 =
  14. 14.900 − 99 =
  15. 15.72 + 29 =
  16. 16.16 + 9 =
  17. 17.70 − 29 =
  18. 18.78 + 19 =
  19. 19.71 − 19 =
  20. 20.13 − 9 =
  21. 21.21 + 29 =
  22. 22.57 − 29 =
  23. 23.351 + 99 =
  24. 24.32 + 29 =
  25. 25.30 − 19 =
  26. 26.23 + 9 =
  27. 27.42 + 9 =
  28. 28.83 − 29 =
  29. 29.423 − 99 =
  30. 30.12 + 9 =
  31. 31.27 − 19 =
  32. 32.74 + 19 =
  33. 33.24 + 29 =
  34. 34.438 − 99 =
  35. 35.62 + 29 =
  36. 36.57 + 19 =
  37. 37.56 + 9 =
  38. 38.528 + 99 =
  39. 39.47 − 29 =
  40. 40.98 − 29 =

Answer key

  1. 70
  2. 786
  3. 23
  4. 54
  5. 68
  6. 581
  7. 317
  8. 52
  9. 85
  10. 65
  11. 56
  12. 43
  13. 65
  14. 801
  15. 101
  16. 25
  17. 41
  18. 97
  19. 52
  20. 4
  21. 50
  22. 28
  23. 450
  24. 61
  25. 11
  26. 32
  27. 51
  28. 54
  29. 324
  30. 21
  31. 8
  32. 93
  33. 53
  34. 339
  35. 91
  36. 76
  37. 65
  38. 627
  39. 18
  40. 69

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