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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 25 · 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. 1.52 − 9 =
  2. 2.79 − 19 =
  3. 3.225 + 99 =
  4. 4.19 − 9 =
  5. 5.39 + 29 =
  6. 6.105 − 29 =
  7. 7.53 − 9 =
  8. 8.194 + 99 =
  9. 9.38 + 9 =
  10. 10.55 + 9 =
  11. 11.35 + 19 =
  12. 12.68 + 9 =
  13. 13.41 + 29 =
  14. 14.16 + 19 =
  15. 15.99 − 19 =
  16. 16.21 − 9 =
  17. 17.77 + 9 =
  18. 18.30 + 9 =
  19. 19.21 + 29 =
  20. 20.13 + 9 =
  21. 21.23 − 9 =
  22. 22.186 + 99 =
  23. 23.60 − 19 =
  24. 24.857 − 99 =
  25. 25.886 − 99 =
  26. 26.17 + 9 =
  27. 27.50 + 29 =
  28. 28.23 + 19 =
  29. 29.38 − 9 =
  30. 30.39 − 29 =
  31. 31.55 + 19 =
  32. 32.549 − 99 =
  33. 33.68 + 19 =
  34. 34.31 + 29 =
  35. 35.51 + 9 =
  36. 36.40 + 29 =
  37. 37.284 + 99 =
  38. 38.77 − 19 =
  39. 39.57 + 9 =
  40. 40.727 − 99 =

Answer key

  1. 43
  2. 60
  3. 324
  4. 10
  5. 68
  6. 76
  7. 44
  8. 293
  9. 47
  10. 64
  11. 54
  12. 77
  13. 70
  14. 35
  15. 80
  16. 12
  17. 86
  18. 39
  19. 50
  20. 22
  21. 14
  22. 285
  23. 41
  24. 758
  25. 787
  26. 26
  27. 79
  28. 42
  29. 29
  30. 10
  31. 74
  32. 450
  33. 87
  34. 60
  35. 60
  36. 69
  37. 383
  38. 58
  39. 66
  40. 628

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