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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 969 · 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. 1.16 − 9 =
  2. 2.16 + 9 =
  3. 3.18 + 29 =
  4. 4.79 + 9 =
  5. 5.297 + 99 =
  6. 6.89 − 9 =
  7. 7.30 + 19 =
  8. 8.31 − 9 =
  9. 9.41 + 29 =
  10. 10.80 + 29 =
  11. 11.27 + 9 =
  12. 12.72 + 29 =
  13. 13.43 − 29 =
  14. 14.65 − 19 =
  15. 15.91 − 29 =
  16. 16.49 − 9 =
  17. 17.53 + 9 =
  18. 18.28 − 9 =
  19. 19.599 − 99 =
  20. 20.98 − 29 =
  21. 21.17 + 19 =
  22. 22.72 + 9 =
  23. 23.26 − 19 =
  24. 24.93 − 29 =
  25. 25.285 − 99 =
  26. 26.79 − 9 =
  27. 27.33 + 9 =
  28. 28.62 + 29 =
  29. 29.64 − 19 =
  30. 30.74 − 19 =
  31. 31.27 + 19 =
  32. 32.76 + 9 =
  33. 33.633 − 99 =
  34. 34.52 − 9 =
  35. 35.734 + 99 =
  36. 36.97 − 29 =
  37. 37.39 − 19 =
  38. 38.677 − 99 =
  39. 39.47 + 19 =
  40. 40.69 − 29 =

Answer key

  1. 7
  2. 25
  3. 47
  4. 88
  5. 396
  6. 80
  7. 49
  8. 22
  9. 70
  10. 109
  11. 36
  12. 101
  13. 14
  14. 46
  15. 62
  16. 40
  17. 62
  18. 19
  19. 500
  20. 69
  21. 36
  22. 81
  23. 7
  24. 64
  25. 186
  26. 70
  27. 42
  28. 91
  29. 45
  30. 55
  31. 46
  32. 85
  33. 534
  34. 43
  35. 833
  36. 68
  37. 20
  38. 578
  39. 66
  40. 40

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