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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 940 · 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. 1.69 + 29 =
  2. 2.28 + 19 =
  3. 3.81 − 19 =
  4. 4.442 + 99 =
  5. 5.380 − 99 =
  6. 6.16 − 9 =
  7. 7.39 + 29 =
  8. 8.50 − 19 =
  9. 9.26 + 19 =
  10. 10.47 + 19 =
  11. 11.418 + 99 =
  12. 12.170 + 99 =
  13. 13.41 − 19 =
  14. 14.31 − 9 =
  15. 15.40 − 19 =
  16. 16.54 + 29 =
  17. 17.466 − 99 =
  18. 18.88 − 29 =
  19. 19.20 + 29 =
  20. 20.69 + 19 =
  21. 21.13 + 29 =
  22. 22.67 + 19 =
  23. 23.18 + 29 =
  24. 24.37 + 29 =
  25. 25.68 − 9 =
  26. 26.94 − 29 =
  27. 27.66 + 9 =
  28. 28.38 + 19 =
  29. 29.34 + 9 =
  30. 30.17 − 9 =
  31. 31.315 − 99 =
  32. 32.33 + 19 =
  33. 33.494 + 99 =
  34. 34.353 + 99 =
  35. 35.603 − 99 =
  36. 36.22 + 9 =
  37. 37.12 + 9 =
  38. 38.73 + 29 =
  39. 39.74 − 9 =
  40. 40.453 − 99 =

Answer key

  1. 98
  2. 47
  3. 62
  4. 541
  5. 281
  6. 7
  7. 68
  8. 31
  9. 45
  10. 66
  11. 517
  12. 269
  13. 22
  14. 22
  15. 21
  16. 83
  17. 367
  18. 59
  19. 49
  20. 88
  21. 42
  22. 86
  23. 47
  24. 66
  25. 59
  26. 65
  27. 75
  28. 57
  29. 43
  30. 8
  31. 216
  32. 52
  33. 593
  34. 452
  35. 504
  36. 31
  37. 21
  38. 102
  39. 65
  40. 354

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