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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 816 · 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. 1.22 − 9 =
  2. 2.48 + 9 =
  3. 3.30 − 19 =
  4. 4.80 + 19 =
  5. 5.80 − 19 =
  6. 6.35 − 9 =
  7. 7.61 − 9 =
  8. 8.71 + 9 =
  9. 9.143 + 99 =
  10. 10.315 + 99 =
  11. 11.141 + 99 =
  12. 12.31 + 29 =
  13. 13.237 − 99 =
  14. 14.69 − 19 =
  15. 15.255 − 99 =
  16. 16.47 − 29 =
  17. 17.55 − 9 =
  18. 18.672 + 99 =
  19. 19.67 + 19 =
  20. 20.73 + 19 =
  21. 21.57 + 9 =
  22. 22.91 − 19 =
  23. 23.869 − 99 =
  24. 24.620 − 99 =
  25. 25.324 − 99 =
  26. 26.77 − 9 =
  27. 27.66 + 19 =
  28. 28.696 + 99 =
  29. 29.89 − 19 =
  30. 30.264 + 99 =
  31. 31.462 + 99 =
  32. 32.30 + 9 =
  33. 33.708 + 99 =
  34. 34.44 − 9 =
  35. 35.356 + 99 =
  36. 36.13 + 29 =
  37. 37.62 − 9 =
  38. 38.54 − 9 =
  39. 39.39 + 19 =
  40. 40.78 − 29 =

Answer key

  1. 13
  2. 57
  3. 11
  4. 99
  5. 61
  6. 26
  7. 52
  8. 80
  9. 242
  10. 414
  11. 240
  12. 60
  13. 138
  14. 50
  15. 156
  16. 18
  17. 46
  18. 771
  19. 86
  20. 92
  21. 66
  22. 72
  23. 770
  24. 521
  25. 225
  26. 68
  27. 85
  28. 795
  29. 70
  30. 363
  31. 561
  32. 39
  33. 807
  34. 35
  35. 455
  36. 42
  37. 53
  38. 45
  39. 58
  40. 49

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