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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 277 · 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. 1.80 − 29 =
  2. 2.103 − 29 =
  3. 3.475 − 99 =
  4. 4.65 + 29 =
  5. 5.35 − 9 =
  6. 6.37 − 19 =
  7. 7.62 − 9 =
  8. 8.50 − 9 =
  9. 9.70 + 29 =
  10. 10.91 − 19 =
  11. 11.530 + 99 =
  12. 12.22 − 19 =
  13. 13.30 − 9 =
  14. 14.50 − 19 =
  15. 15.62 − 19 =
  16. 16.12 + 19 =
  17. 17.48 − 9 =
  18. 18.53 + 29 =
  19. 19.46 − 29 =
  20. 20.60 + 19 =
  21. 21.13 − 9 =
  22. 22.43 − 9 =
  23. 23.15 − 9 =
  24. 24.512 − 99 =
  25. 25.38 − 9 =
  26. 26.42 + 29 =
  27. 27.85 − 9 =
  28. 28.79 + 19 =
  29. 29.39 + 9 =
  30. 30.72 + 29 =
  31. 31.97 − 29 =
  32. 32.46 − 9 =
  33. 33.14 + 9 =
  34. 34.33 − 29 =
  35. 35.26 + 19 =
  36. 36.52 + 19 =
  37. 37.29 + 29 =
  38. 38.888 − 99 =
  39. 39.230 + 99 =
  40. 40.76 − 29 =

Answer key

  1. 51
  2. 74
  3. 376
  4. 94
  5. 26
  6. 18
  7. 53
  8. 41
  9. 99
  10. 72
  11. 629
  12. 3
  13. 21
  14. 31
  15. 43
  16. 31
  17. 39
  18. 82
  19. 17
  20. 79
  21. 4
  22. 34
  23. 6
  24. 413
  25. 29
  26. 71
  27. 76
  28. 98
  29. 48
  30. 101
  31. 68
  32. 37
  33. 23
  34. 4
  35. 45
  36. 71
  37. 58
  38. 789
  39. 329
  40. 47

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