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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 296 · 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. 1.31 + 29 =
  2. 2.43 + 19 =
  3. 3.76 − 29 =
  4. 4.54 + 29 =
  5. 5.43 + 29 =
  6. 6.374 + 99 =
  7. 7.60 − 9 =
  8. 8.287 − 99 =
  9. 9.93 − 19 =
  10. 10.395 − 99 =
  11. 11.27 + 9 =
  12. 12.36 + 9 =
  13. 13.59 − 29 =
  14. 14.29 − 9 =
  15. 15.433 + 99 =
  16. 16.77 + 9 =
  17. 17.64 + 19 =
  18. 18.68 + 9 =
  19. 19.31 − 9 =
  20. 20.46 + 19 =
  21. 21.386 − 99 =
  22. 22.38 + 29 =
  23. 23.15 − 9 =
  24. 24.38 − 19 =
  25. 25.32 + 9 =
  26. 26.42 + 29 =
  27. 27.39 − 19 =
  28. 28.81 − 9 =
  29. 29.61 + 9 =
  30. 30.582 − 99 =
  31. 31.34 − 9 =
  32. 32.831 − 99 =
  33. 33.95 − 29 =
  34. 34.20 + 9 =
  35. 35.71 + 19 =
  36. 36.25 + 9 =
  37. 37.605 − 99 =
  38. 38.39 − 9 =
  39. 39.86 − 19 =
  40. 40.49 + 19 =

Answer key

  1. 60
  2. 62
  3. 47
  4. 83
  5. 72
  6. 473
  7. 51
  8. 188
  9. 74
  10. 296
  11. 36
  12. 45
  13. 30
  14. 20
  15. 532
  16. 86
  17. 83
  18. 77
  19. 22
  20. 65
  21. 287
  22. 67
  23. 6
  24. 19
  25. 41
  26. 71
  27. 20
  28. 72
  29. 70
  30. 483
  31. 25
  32. 732
  33. 66
  34. 29
  35. 90
  36. 34
  37. 506
  38. 30
  39. 67
  40. 68

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