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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 952 · 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 + 9 =
  2. 2.37 − 19 =
  3. 3.79 + 19 =
  4. 4.41 − 9 =
  5. 5.38 + 29 =
  6. 6.27 + 9 =
  7. 7.77 + 29 =
  8. 8.81 − 9 =
  9. 9.25 + 29 =
  10. 10.440 − 99 =
  11. 11.501 − 99 =
  12. 12.17 − 9 =
  13. 13.70 + 19 =
  14. 14.305 + 99 =
  15. 15.46 − 9 =
  16. 16.87 − 19 =
  17. 17.98 − 29 =
  18. 18.42 − 29 =
  19. 19.13 − 9 =
  20. 20.326 + 99 =
  21. 21.755 + 99 =
  22. 22.200 + 99 =
  23. 23.52 + 9 =
  24. 24.28 − 19 =
  25. 25.57 − 19 =
  26. 26.611 + 99 =
  27. 27.687 − 99 =
  28. 28.620 + 99 =
  29. 29.57 − 9 =
  30. 30.56 + 29 =
  31. 31.75 − 9 =
  32. 32.38 + 19 =
  33. 33.54 − 9 =
  34. 34.40 − 29 =
  35. 35.27 + 19 =
  36. 36.323 + 99 =
  37. 37.94 − 29 =
  38. 38.59 − 9 =
  39. 39.28 + 19 =
  40. 40.44 + 9 =

Answer key

  1. 37
  2. 18
  3. 98
  4. 32
  5. 67
  6. 36
  7. 106
  8. 72
  9. 54
  10. 341
  11. 402
  12. 8
  13. 89
  14. 404
  15. 37
  16. 68
  17. 69
  18. 13
  19. 4
  20. 425
  21. 854
  22. 299
  23. 61
  24. 9
  25. 38
  26. 710
  27. 588
  28. 719
  29. 48
  30. 85
  31. 66
  32. 57
  33. 45
  34. 11
  35. 46
  36. 422
  37. 65
  38. 50
  39. 47
  40. 53

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