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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 714 · 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 + 19 =
  2. 2.32 − 29 =
  3. 3.167 + 99 =
  4. 4.77 + 9 =
  5. 5.66 + 19 =
  6. 6.43 + 19 =
  7. 7.62 + 9 =
  8. 8.80 − 9 =
  9. 9.52 − 9 =
  10. 10.54 + 9 =
  11. 11.235 + 99 =
  12. 12.775 − 99 =
  13. 13.62 − 19 =
  14. 14.28 − 19 =
  15. 15.55 − 19 =
  16. 16.35 − 29 =
  17. 17.64 + 9 =
  18. 18.482 − 99 =
  19. 19.289 − 99 =
  20. 20.75 − 19 =
  21. 21.635 − 99 =
  22. 22.42 + 29 =
  23. 23.458 + 99 =
  24. 24.250 − 99 =
  25. 25.418 + 99 =
  26. 26.32 − 19 =
  27. 27.27 − 9 =
  28. 28.81 − 19 =
  29. 29.62 − 29 =
  30. 30.61 − 19 =
  31. 31.38 + 29 =
  32. 32.57 + 19 =
  33. 33.66 − 9 =
  34. 34.89 − 29 =
  35. 35.26 + 19 =
  36. 36.80 + 19 =
  37. 37.79 − 9 =
  38. 38.90 − 19 =
  39. 39.64 + 29 =
  40. 40.46 + 29 =

Answer key

  1. 91
  2. 3
  3. 266
  4. 86
  5. 85
  6. 62
  7. 71
  8. 71
  9. 43
  10. 63
  11. 334
  12. 676
  13. 43
  14. 9
  15. 36
  16. 6
  17. 73
  18. 383
  19. 190
  20. 56
  21. 536
  22. 71
  23. 557
  24. 151
  25. 517
  26. 13
  27. 18
  28. 62
  29. 33
  30. 42
  31. 67
  32. 76
  33. 57
  34. 60
  35. 45
  36. 99
  37. 70
  38. 71
  39. 93
  40. 75

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