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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 198 · 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. 1.30 + 9 =
  2. 2.50 + 9 =
  3. 3.40 + 19 =
  4. 4.61 + 19 =
  5. 5.78 − 19 =
  6. 6.660 − 99 =
  7. 7.19 + 9 =
  8. 8.21 + 9 =
  9. 9.78 + 29 =
  10. 10.597 + 99 =
  11. 11.662 + 99 =
  12. 12.65 − 29 =
  13. 13.615 + 99 =
  14. 14.66 + 9 =
  15. 15.48 + 29 =
  16. 16.70 + 9 =
  17. 17.51 + 9 =
  18. 18.181 + 99 =
  19. 19.62 + 29 =
  20. 20.41 − 19 =
  21. 21.94 − 19 =
  22. 22.62 − 9 =
  23. 23.109 − 29 =
  24. 24.64 − 29 =
  25. 25.325 − 99 =
  26. 26.18 − 9 =
  27. 27.569 + 99 =
  28. 28.28 + 19 =
  29. 29.93 − 19 =
  30. 30.78 − 9 =
  31. 31.32 + 9 =
  32. 32.61 − 29 =
  33. 33.537 + 99 =
  34. 34.42 + 29 =
  35. 35.39 + 19 =
  36. 36.74 + 19 =
  37. 37.51 + 19 =
  38. 38.44 + 9 =
  39. 39.101 − 29 =
  40. 40.20 + 29 =

Answer key

  1. 39
  2. 59
  3. 59
  4. 80
  5. 59
  6. 561
  7. 28
  8. 30
  9. 107
  10. 696
  11. 761
  12. 36
  13. 714
  14. 75
  15. 77
  16. 79
  17. 60
  18. 280
  19. 91
  20. 22
  21. 75
  22. 53
  23. 80
  24. 35
  25. 226
  26. 9
  27. 668
  28. 47
  29. 74
  30. 69
  31. 41
  32. 32
  33. 636
  34. 71
  35. 58
  36. 93
  37. 70
  38. 53
  39. 72
  40. 49

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