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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 922 · 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. 1.50 − 29 =
  2. 2.86 − 19 =
  3. 3.22 + 29 =
  4. 4.253 + 99 =
  5. 5.362 + 99 =
  6. 6.46 + 29 =
  7. 7.507 + 99 =
  8. 8.75 + 29 =
  9. 9.60 − 9 =
  10. 10.29 + 29 =
  11. 11.38 + 29 =
  12. 12.25 + 9 =
  13. 13.60 + 9 =
  14. 14.36 − 9 =
  15. 15.151 + 99 =
  16. 16.78 + 19 =
  17. 17.48 − 9 =
  18. 18.35 + 9 =
  19. 19.71 − 19 =
  20. 20.131 + 99 =
  21. 21.343 − 99 =
  22. 22.108 − 29 =
  23. 23.16 + 9 =
  24. 24.18 + 29 =
  25. 25.30 + 29 =
  26. 26.20 + 9 =
  27. 27.25 − 9 =
  28. 28.543 + 99 =
  29. 29.266 − 99 =
  30. 30.313 − 99 =
  31. 31.46 − 9 =
  32. 32.70 + 9 =
  33. 33.44 − 19 =
  34. 34.20 + 19 =
  35. 35.52 + 19 =
  36. 36.423 + 99 =
  37. 37.69 − 29 =
  38. 38.69 − 19 =
  39. 39.475 + 99 =
  40. 40.26 − 9 =

Answer key

  1. 21
  2. 67
  3. 51
  4. 352
  5. 461
  6. 75
  7. 606
  8. 104
  9. 51
  10. 58
  11. 67
  12. 34
  13. 69
  14. 27
  15. 250
  16. 97
  17. 39
  18. 44
  19. 52
  20. 230
  21. 244
  22. 79
  23. 25
  24. 47
  25. 59
  26. 29
  27. 16
  28. 642
  29. 167
  30. 214
  31. 37
  32. 79
  33. 25
  34. 39
  35. 71
  36. 522
  37. 40
  38. 50
  39. 574
  40. 17

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