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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 243 · 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. 1.46 − 19 =
  2. 2.35 − 9 =
  3. 3.290 + 99 =
  4. 4.213 + 99 =
  5. 5.891 − 99 =
  6. 6.535 + 99 =
  7. 7.59 − 9 =
  8. 8.20 + 29 =
  9. 9.235 + 99 =
  10. 10.97 − 19 =
  11. 11.92 − 19 =
  12. 12.57 + 9 =
  13. 13.457 + 99 =
  14. 14.262 − 99 =
  15. 15.71 + 9 =
  16. 16.241 + 99 =
  17. 17.642 − 99 =
  18. 18.24 + 9 =
  19. 19.18 + 19 =
  20. 20.78 − 29 =
  21. 21.42 + 29 =
  22. 22.579 − 99 =
  23. 23.77 − 9 =
  24. 24.48 + 29 =
  25. 25.538 − 99 =
  26. 26.49 − 29 =
  27. 27.24 − 19 =
  28. 28.19 + 29 =
  29. 29.59 + 29 =
  30. 30.662 − 99 =
  31. 31.875 − 99 =
  32. 32.50 − 9 =
  33. 33.19 + 19 =
  34. 34.42 − 29 =
  35. 35.48 − 19 =
  36. 36.29 + 9 =
  37. 37.506 + 99 =
  38. 38.69 + 19 =
  39. 39.42 + 19 =
  40. 40.71 − 9 =

Answer key

  1. 27
  2. 26
  3. 389
  4. 312
  5. 792
  6. 634
  7. 50
  8. 49
  9. 334
  10. 78
  11. 73
  12. 66
  13. 556
  14. 163
  15. 80
  16. 340
  17. 543
  18. 33
  19. 37
  20. 49
  21. 71
  22. 480
  23. 68
  24. 77
  25. 439
  26. 20
  27. 5
  28. 48
  29. 88
  30. 563
  31. 776
  32. 41
  33. 38
  34. 13
  35. 29
  36. 38
  37. 605
  38. 88
  39. 61
  40. 62

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