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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 149 · 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. 1.91 − 19 =
  2. 2.23 + 29 =
  3. 3.69 + 19 =
  4. 4.316 + 99 =
  5. 5.538 + 99 =
  6. 6.46 + 29 =
  7. 7.513 − 99 =
  8. 8.42 − 29 =
  9. 9.364 + 99 =
  10. 10.88 − 19 =
  11. 11.220 − 99 =
  12. 12.77 + 19 =
  13. 13.68 + 9 =
  14. 14.427 + 99 =
  15. 15.788 − 99 =
  16. 16.80 + 9 =
  17. 17.284 + 99 =
  18. 18.71 − 19 =
  19. 19.19 + 9 =
  20. 20.744 + 99 =
  21. 21.15 + 19 =
  22. 22.23 + 9 =
  23. 23.35 − 29 =
  24. 24.514 − 99 =
  25. 25.47 + 29 =
  26. 26.867 − 99 =
  27. 27.63 + 9 =
  28. 28.35 − 9 =
  29. 29.49 + 19 =
  30. 30.57 − 19 =
  31. 31.22 + 19 =
  32. 32.38 + 19 =
  33. 33.370 + 99 =
  34. 34.62 − 9 =
  35. 35.62 + 19 =
  36. 36.100 − 29 =
  37. 37.22 + 29 =
  38. 38.338 − 99 =
  39. 39.99 − 19 =
  40. 40.61 + 19 =

Answer key

  1. 72
  2. 52
  3. 88
  4. 415
  5. 637
  6. 75
  7. 414
  8. 13
  9. 463
  10. 69
  11. 121
  12. 96
  13. 77
  14. 526
  15. 689
  16. 89
  17. 383
  18. 52
  19. 28
  20. 843
  21. 34
  22. 32
  23. 6
  24. 415
  25. 76
  26. 768
  27. 72
  28. 26
  29. 68
  30. 38
  31. 41
  32. 57
  33. 469
  34. 53
  35. 81
  36. 71
  37. 51
  38. 239
  39. 80
  40. 80

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