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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 526 · 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. 1.89 − 19 =
  2. 2.20 − 9 =
  3. 3.94 − 19 =
  4. 4.41 + 19 =
  5. 5.41 + 9 =
  6. 6.77 + 19 =
  7. 7.51 + 9 =
  8. 8.37 + 9 =
  9. 9.57 − 9 =
  10. 10.46 + 9 =
  11. 11.43 + 19 =
  12. 12.43 − 19 =
  13. 13.633 + 99 =
  14. 14.29 − 19 =
  15. 15.24 + 19 =
  16. 16.725 + 99 =
  17. 17.106 − 29 =
  18. 18.35 + 29 =
  19. 19.73 − 19 =
  20. 20.300 − 99 =
  21. 21.78 + 29 =
  22. 22.43 + 29 =
  23. 23.331 + 99 =
  24. 24.35 − 19 =
  25. 25.69 + 9 =
  26. 26.40 + 19 =
  27. 27.41 + 29 =
  28. 28.36 − 9 =
  29. 29.55 − 9 =
  30. 30.22 + 19 =
  31. 31.22 + 9 =
  32. 32.47 + 19 =
  33. 33.28 + 9 =
  34. 34.92 − 29 =
  35. 35.71 − 19 =
  36. 36.55 + 19 =
  37. 37.32 − 9 =
  38. 38.714 − 99 =
  39. 39.755 − 99 =
  40. 40.33 + 29 =

Answer key

  1. 70
  2. 11
  3. 75
  4. 60
  5. 50
  6. 96
  7. 60
  8. 46
  9. 48
  10. 55
  11. 62
  12. 24
  13. 732
  14. 10
  15. 43
  16. 824
  17. 77
  18. 64
  19. 54
  20. 201
  21. 107
  22. 72
  23. 430
  24. 16
  25. 78
  26. 59
  27. 70
  28. 27
  29. 46
  30. 41
  31. 31
  32. 66
  33. 37
  34. 63
  35. 52
  36. 74
  37. 23
  38. 615
  39. 656
  40. 62

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