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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 555 · 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. 1.35 − 29 =
  2. 2.48 + 19 =
  3. 3.38 − 9 =
  4. 4.25 − 9 =
  5. 5.54 − 19 =
  6. 6.44 − 29 =
  7. 7.29 − 19 =
  8. 8.66 + 19 =
  9. 9.83 − 19 =
  10. 10.263 − 99 =
  11. 11.52 + 29 =
  12. 12.13 + 19 =
  13. 13.779 − 99 =
  14. 14.43 + 29 =
  15. 15.32 + 29 =
  16. 16.63 − 9 =
  17. 17.240 − 99 =
  18. 18.47 + 19 =
  19. 19.42 + 19 =
  20. 20.40 + 9 =
  21. 21.68 + 29 =
  22. 22.61 − 19 =
  23. 23.25 − 19 =
  24. 24.70 + 9 =
  25. 25.30 + 9 =
  26. 26.35 − 9 =
  27. 27.34 + 9 =
  28. 28.52 + 9 =
  29. 29.78 − 19 =
  30. 30.77 − 19 =
  31. 31.42 + 29 =
  32. 32.89 − 19 =
  33. 33.13 − 9 =
  34. 34.35 + 19 =
  35. 35.73 + 9 =
  36. 36.760 + 99 =
  37. 37.73 − 9 =
  38. 38.29 + 9 =
  39. 39.34 − 9 =
  40. 40.39 − 9 =

Answer key

  1. 6
  2. 67
  3. 29
  4. 16
  5. 35
  6. 15
  7. 10
  8. 85
  9. 64
  10. 164
  11. 81
  12. 32
  13. 680
  14. 72
  15. 61
  16. 54
  17. 141
  18. 66
  19. 61
  20. 49
  21. 97
  22. 42
  23. 6
  24. 79
  25. 39
  26. 26
  27. 43
  28. 61
  29. 59
  30. 58
  31. 71
  32. 70
  33. 4
  34. 54
  35. 82
  36. 859
  37. 64
  38. 38
  39. 25
  40. 30

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