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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 542 · 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. 1.55 + 19 =
  2. 2.33 + 19 =
  3. 3.75 + 29 =
  4. 4.26 + 9 =
  5. 5.92 − 29 =
  6. 6.595 + 99 =
  7. 7.76 − 19 =
  8. 8.13 − 9 =
  9. 9.78 − 29 =
  10. 10.17 + 19 =
  11. 11.20 + 29 =
  12. 12.40 − 19 =
  13. 13.51 − 19 =
  14. 14.56 + 9 =
  15. 15.67 − 29 =
  16. 16.54 + 19 =
  17. 17.742 + 99 =
  18. 18.53 − 19 =
  19. 19.40 + 9 =
  20. 20.32 − 9 =
  21. 21.52 + 9 =
  22. 22.18 + 9 =
  23. 23.547 + 99 =
  24. 24.37 − 9 =
  25. 25.23 − 19 =
  26. 26.65 + 29 =
  27. 27.478 − 99 =
  28. 28.32 − 29 =
  29. 29.29 + 9 =
  30. 30.12 − 9 =
  31. 31.43 + 19 =
  32. 32.79 − 9 =
  33. 33.630 + 99 =
  34. 34.22 + 29 =
  35. 35.51 − 9 =
  36. 36.19 + 9 =
  37. 37.845 − 99 =
  38. 38.265 + 99 =
  39. 39.504 − 99 =
  40. 40.39 − 29 =

Answer key

  1. 74
  2. 52
  3. 104
  4. 35
  5. 63
  6. 694
  7. 57
  8. 4
  9. 49
  10. 36
  11. 49
  12. 21
  13. 32
  14. 65
  15. 38
  16. 73
  17. 841
  18. 34
  19. 49
  20. 23
  21. 61
  22. 27
  23. 646
  24. 28
  25. 4
  26. 94
  27. 379
  28. 3
  29. 38
  30. 3
  31. 62
  32. 70
  33. 729
  34. 51
  35. 42
  36. 28
  37. 746
  38. 364
  39. 405
  40. 10

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