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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 135 · 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. 1.22 + 19 =
  2. 2.514 − 99 =
  3. 3.75 − 9 =
  4. 4.61 + 9 =
  5. 5.15 + 19 =
  6. 6.81 − 29 =
  7. 7.34 − 9 =
  8. 8.16 + 29 =
  9. 9.25 − 19 =
  10. 10.95 − 29 =
  11. 11.94 − 29 =
  12. 12.16 + 9 =
  13. 13.77 − 29 =
  14. 14.65 − 9 =
  15. 15.78 + 19 =
  16. 16.66 + 9 =
  17. 17.38 − 29 =
  18. 18.42 − 19 =
  19. 19.72 + 9 =
  20. 20.84 − 29 =
  21. 21.346 + 99 =
  22. 22.29 + 29 =
  23. 23.49 − 9 =
  24. 24.20 − 9 =
  25. 25.56 + 19 =
  26. 26.444 − 99 =
  27. 27.40 + 29 =
  28. 28.46 + 9 =
  29. 29.88 − 9 =
  30. 30.55 + 9 =
  31. 31.254 − 99 =
  32. 32.23 + 19 =
  33. 33.18 − 9 =
  34. 34.71 + 9 =
  35. 35.67 + 29 =
  36. 36.79 − 9 =
  37. 37.30 − 19 =
  38. 38.67 + 9 =
  39. 39.68 + 9 =
  40. 40.15 − 9 =

Answer key

  1. 41
  2. 415
  3. 66
  4. 70
  5. 34
  6. 52
  7. 25
  8. 45
  9. 6
  10. 66
  11. 65
  12. 25
  13. 48
  14. 56
  15. 97
  16. 75
  17. 9
  18. 23
  19. 81
  20. 55
  21. 445
  22. 58
  23. 40
  24. 11
  25. 75
  26. 345
  27. 69
  28. 55
  29. 79
  30. 64
  31. 155
  32. 42
  33. 9
  34. 80
  35. 96
  36. 70
  37. 11
  38. 76
  39. 77
  40. 6

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