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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 600 · 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. 1.28 + 19 =
  2. 2.69 + 29 =
  3. 3.63 − 19 =
  4. 4.73 − 9 =
  5. 5.36 − 19 =
  6. 6.48 − 9 =
  7. 7.46 + 19 =
  8. 8.226 + 99 =
  9. 9.776 − 99 =
  10. 10.48 − 29 =
  11. 11.46 + 29 =
  12. 12.81 − 9 =
  13. 13.615 + 99 =
  14. 14.480 − 99 =
  15. 15.72 − 9 =
  16. 16.63 − 9 =
  17. 17.58 + 9 =
  18. 18.51 + 9 =
  19. 19.47 + 29 =
  20. 20.38 − 9 =
  21. 21.49 − 19 =
  22. 22.38 − 29 =
  23. 23.79 − 29 =
  24. 24.213 − 99 =
  25. 25.647 − 99 =
  26. 26.19 − 9 =
  27. 27.46 − 29 =
  28. 28.47 + 9 =
  29. 29.64 + 9 =
  30. 30.16 + 29 =
  31. 31.90 − 29 =
  32. 32.13 − 9 =
  33. 33.78 + 9 =
  34. 34.54 − 29 =
  35. 35.12 + 29 =
  36. 36.53 + 29 =
  37. 37.60 + 29 =
  38. 38.319 − 99 =
  39. 39.31 + 29 =
  40. 40.52 + 19 =

Answer key

  1. 47
  2. 98
  3. 44
  4. 64
  5. 17
  6. 39
  7. 65
  8. 325
  9. 677
  10. 19
  11. 75
  12. 72
  13. 714
  14. 381
  15. 63
  16. 54
  17. 67
  18. 60
  19. 76
  20. 29
  21. 30
  22. 9
  23. 50
  24. 114
  25. 548
  26. 10
  27. 17
  28. 56
  29. 73
  30. 45
  31. 61
  32. 4
  33. 87
  34. 25
  35. 41
  36. 82
  37. 89
  38. 220
  39. 60
  40. 71

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