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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 181 · 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. 1.66 − 9 =
  2. 2.771 + 99 =
  3. 3.40 + 29 =
  4. 4.40 + 19 =
  5. 5.49 + 19 =
  6. 6.54 − 29 =
  7. 7.17 − 9 =
  8. 8.656 + 99 =
  9. 9.65 + 29 =
  10. 10.29 − 19 =
  11. 11.253 − 99 =
  12. 12.26 − 9 =
  13. 13.29 − 9 =
  14. 14.466 − 99 =
  15. 15.179 + 99 =
  16. 16.882 − 99 =
  17. 17.250 + 99 =
  18. 18.70 − 9 =
  19. 19.36 − 9 =
  20. 20.368 + 99 =
  21. 21.19 + 29 =
  22. 22.38 + 29 =
  23. 23.71 − 29 =
  24. 24.166 + 99 =
  25. 25.59 + 29 =
  26. 26.472 − 99 =
  27. 27.845 − 99 =
  28. 28.238 + 99 =
  29. 29.22 + 19 =
  30. 30.25 + 9 =
  31. 31.15 − 9 =
  32. 32.79 + 9 =
  33. 33.61 + 9 =
  34. 34.32 − 9 =
  35. 35.35 + 19 =
  36. 36.52 − 9 =
  37. 37.822 − 99 =
  38. 38.35 + 9 =
  39. 39.78 + 29 =
  40. 40.41 + 9 =

Answer key

  1. 57
  2. 870
  3. 69
  4. 59
  5. 68
  6. 25
  7. 8
  8. 755
  9. 94
  10. 10
  11. 154
  12. 17
  13. 20
  14. 367
  15. 278
  16. 783
  17. 349
  18. 61
  19. 27
  20. 467
  21. 48
  22. 67
  23. 42
  24. 265
  25. 88
  26. 373
  27. 746
  28. 337
  29. 41
  30. 34
  31. 6
  32. 88
  33. 70
  34. 23
  35. 54
  36. 43
  37. 723
  38. 44
  39. 107
  40. 50

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