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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 658 · 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 − 9 =
  2. 2.418 − 99 =
  3. 3.96 − 29 =
  4. 4.36 − 9 =
  5. 5.70 − 9 =
  6. 6.63 − 9 =
  7. 7.37 − 9 =
  8. 8.64 + 9 =
  9. 9.414 − 99 =
  10. 10.16 − 9 =
  11. 11.99 − 19 =
  12. 12.78 + 19 =
  13. 13.69 + 29 =
  14. 14.91 − 19 =
  15. 15.795 − 99 =
  16. 16.67 + 9 =
  17. 17.314 − 99 =
  18. 18.113 + 99 =
  19. 19.95 − 19 =
  20. 20.16 + 9 =
  21. 21.65 + 9 =
  22. 22.77 + 29 =
  23. 23.868 − 99 =
  24. 24.19 − 9 =
  25. 25.680 + 99 =
  26. 26.63 + 9 =
  27. 27.199 + 99 =
  28. 28.62 − 19 =
  29. 29.15 + 19 =
  30. 30.569 − 99 =
  31. 31.49 + 9 =
  32. 32.46 − 9 =
  33. 33.532 − 99 =
  34. 34.424 + 99 =
  35. 35.36 + 29 =
  36. 36.43 + 9 =
  37. 37.61 − 19 =
  38. 38.59 + 9 =
  39. 39.54 − 19 =
  40. 40.19 + 9 =

Answer key

  1. 13
  2. 319
  3. 67
  4. 27
  5. 61
  6. 54
  7. 28
  8. 73
  9. 315
  10. 7
  11. 80
  12. 97
  13. 98
  14. 72
  15. 696
  16. 76
  17. 215
  18. 212
  19. 76
  20. 25
  21. 74
  22. 106
  23. 769
  24. 10
  25. 779
  26. 72
  27. 298
  28. 43
  29. 34
  30. 470
  31. 58
  32. 37
  33. 433
  34. 523
  35. 65
  36. 52
  37. 42
  38. 68
  39. 35
  40. 28

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