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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 525 · 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. 1.441 + 99 =
  2. 2.197 + 99 =
  3. 3.568 + 99 =
  4. 4.21 + 9 =
  5. 5.59 + 19 =
  6. 6.62 + 9 =
  7. 7.78 + 19 =
  8. 8.78 − 9 =
  9. 9.47 + 19 =
  10. 10.245 − 99 =
  11. 11.69 − 19 =
  12. 12.820 − 99 =
  13. 13.74 + 19 =
  14. 14.84 − 19 =
  15. 15.16 − 9 =
  16. 16.22 + 19 =
  17. 17.27 − 19 =
  18. 18.78 + 9 =
  19. 19.41 + 9 =
  20. 20.19 + 19 =
  21. 21.59 + 29 =
  22. 22.26 + 29 =
  23. 23.31 + 9 =
  24. 24.60 − 9 =
  25. 25.79 + 29 =
  26. 26.96 − 19 =
  27. 27.29 − 19 =
  28. 28.60 + 19 =
  29. 29.355 + 99 =
  30. 30.554 + 99 =
  31. 31.39 − 29 =
  32. 32.20 + 29 =
  33. 33.34 − 29 =
  34. 34.69 + 29 =
  35. 35.36 − 29 =
  36. 36.60 + 29 =
  37. 37.76 − 9 =
  38. 38.479 − 99 =
  39. 39.106 − 29 =
  40. 40.18 + 19 =

Answer key

  1. 540
  2. 296
  3. 667
  4. 30
  5. 78
  6. 71
  7. 97
  8. 69
  9. 66
  10. 146
  11. 50
  12. 721
  13. 93
  14. 65
  15. 7
  16. 41
  17. 8
  18. 87
  19. 50
  20. 38
  21. 88
  22. 55
  23. 40
  24. 51
  25. 108
  26. 77
  27. 10
  28. 79
  29. 454
  30. 653
  31. 10
  32. 49
  33. 5
  34. 98
  35. 7
  36. 89
  37. 67
  38. 380
  39. 77
  40. 37

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