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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 708 · 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. 1.45 + 19 =
  2. 2.42 + 19 =
  3. 3.70 + 19 =
  4. 4.54 − 29 =
  5. 5.42 + 9 =
  6. 6.64 − 29 =
  7. 7.47 + 9 =
  8. 8.71 + 29 =
  9. 9.18 + 29 =
  10. 10.71 + 19 =
  11. 11.18 − 9 =
  12. 12.557 + 99 =
  13. 13.13 + 19 =
  14. 14.507 + 99 =
  15. 15.86 − 29 =
  16. 16.82 − 9 =
  17. 17.56 − 19 =
  18. 18.79 − 19 =
  19. 19.86 − 9 =
  20. 20.522 + 99 =
  21. 21.61 − 19 =
  22. 22.678 + 99 =
  23. 23.154 − 99 =
  24. 24.17 + 29 =
  25. 25.23 + 9 =
  26. 26.31 − 19 =
  27. 27.31 + 19 =
  28. 28.39 + 29 =
  29. 29.316 + 99 =
  30. 30.32 − 19 =
  31. 31.30 + 29 =
  32. 32.819 − 99 =
  33. 33.75 + 29 =
  34. 34.60 − 9 =
  35. 35.76 − 9 =
  36. 36.92 − 19 =
  37. 37.18 + 9 =
  38. 38.15 + 9 =
  39. 39.74 − 19 =
  40. 40.57 − 9 =

Answer key

  1. 64
  2. 61
  3. 89
  4. 25
  5. 51
  6. 35
  7. 56
  8. 100
  9. 47
  10. 90
  11. 9
  12. 656
  13. 32
  14. 606
  15. 57
  16. 73
  17. 37
  18. 60
  19. 77
  20. 621
  21. 42
  22. 777
  23. 55
  24. 46
  25. 32
  26. 12
  27. 50
  28. 68
  29. 415
  30. 13
  31. 59
  32. 720
  33. 104
  34. 51
  35. 67
  36. 73
  37. 27
  38. 24
  39. 55
  40. 48

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