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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 451 · 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. 1.277 + 99 =
  2. 2.31 − 9 =
  3. 3.65 + 29 =
  4. 4.58 − 9 =
  5. 5.42 − 19 =
  6. 6.75 − 19 =
  7. 7.43 − 29 =
  8. 8.45 + 19 =
  9. 9.36 − 9 =
  10. 10.743 − 99 =
  11. 11.83 − 9 =
  12. 12.40 + 9 =
  13. 13.142 + 99 =
  14. 14.56 + 19 =
  15. 15.855 − 99 =
  16. 16.17 + 19 =
  17. 17.22 + 9 =
  18. 18.72 + 9 =
  19. 19.60 + 29 =
  20. 20.298 + 99 =
  21. 21.470 − 99 =
  22. 22.60 − 9 =
  23. 23.21 + 9 =
  24. 24.710 + 99 =
  25. 25.647 + 99 =
  26. 26.556 + 99 =
  27. 27.515 − 99 =
  28. 28.13 + 29 =
  29. 29.61 + 19 =
  30. 30.72 − 29 =
  31. 31.27 + 9 =
  32. 32.672 + 99 =
  33. 33.802 − 99 =
  34. 34.51 + 19 =
  35. 35.13 + 9 =
  36. 36.80 − 9 =
  37. 37.318 + 99 =
  38. 38.17 + 9 =
  39. 39.14 + 29 =
  40. 40.32 + 9 =

Answer key

  1. 376
  2. 22
  3. 94
  4. 49
  5. 23
  6. 56
  7. 14
  8. 64
  9. 27
  10. 644
  11. 74
  12. 49
  13. 241
  14. 75
  15. 756
  16. 36
  17. 31
  18. 81
  19. 89
  20. 397
  21. 371
  22. 51
  23. 30
  24. 809
  25. 746
  26. 655
  27. 416
  28. 42
  29. 80
  30. 43
  31. 36
  32. 771
  33. 703
  34. 70
  35. 22
  36. 71
  37. 417
  38. 26
  39. 43
  40. 41

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