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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 96 · 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. 1.64 − 19 =
  2. 2.37 − 29 =
  3. 3.36 − 29 =
  4. 4.104 − 29 =
  5. 5.59 + 19 =
  6. 6.27 + 9 =
  7. 7.60 − 29 =
  8. 8.66 − 19 =
  9. 9.16 + 29 =
  10. 10.571 + 99 =
  11. 11.51 − 29 =
  12. 12.26 + 29 =
  13. 13.29 + 19 =
  14. 14.78 − 29 =
  15. 15.46 + 29 =
  16. 16.423 − 99 =
  17. 17.107 − 29 =
  18. 18.57 − 19 =
  19. 19.15 + 19 =
  20. 20.15 − 9 =
  21. 21.22 + 19 =
  22. 22.55 + 19 =
  23. 23.39 − 9 =
  24. 24.28 + 29 =
  25. 25.75 − 29 =
  26. 26.44 + 9 =
  27. 27.677 + 99 =
  28. 28.76 − 29 =
  29. 29.63 + 19 =
  30. 30.294 − 99 =
  31. 31.44 − 9 =
  32. 32.27 + 19 =
  33. 33.64 − 9 =
  34. 34.54 − 19 =
  35. 35.61 + 29 =
  36. 36.762 + 99 =
  37. 37.41 + 29 =
  38. 38.41 + 19 =
  39. 39.62 − 9 =
  40. 40.28 + 19 =

Answer key

  1. 45
  2. 8
  3. 7
  4. 75
  5. 78
  6. 36
  7. 31
  8. 47
  9. 45
  10. 670
  11. 22
  12. 55
  13. 48
  14. 49
  15. 75
  16. 324
  17. 78
  18. 38
  19. 34
  20. 6
  21. 41
  22. 74
  23. 30
  24. 57
  25. 46
  26. 53
  27. 776
  28. 47
  29. 82
  30. 195
  31. 35
  32. 46
  33. 55
  34. 35
  35. 90
  36. 861
  37. 70
  38. 60
  39. 53
  40. 47

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