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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 621 · 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. 1.67 − 9 =
  2. 2.37 + 9 =
  3. 3.104 − 29 =
  4. 4.62 − 9 =
  5. 5.73 + 9 =
  6. 6.24 − 19 =
  7. 7.17 + 9 =
  8. 8.342 − 99 =
  9. 9.33 − 9 =
  10. 10.18 + 19 =
  11. 11.19 + 29 =
  12. 12.59 + 29 =
  13. 13.89 − 29 =
  14. 14.65 + 19 =
  15. 15.67 − 29 =
  16. 16.48 − 19 =
  17. 17.77 + 29 =
  18. 18.500 + 99 =
  19. 19.96 − 19 =
  20. 20.28 + 19 =
  21. 21.141 + 99 =
  22. 22.76 + 19 =
  23. 23.50 + 19 =
  24. 24.776 − 99 =
  25. 25.372 − 99 =
  26. 26.83 − 29 =
  27. 27.40 − 9 =
  28. 28.95 − 29 =
  29. 29.612 + 99 =
  30. 30.36 − 9 =
  31. 31.41 − 29 =
  32. 32.38 + 19 =
  33. 33.54 − 9 =
  34. 34.79 + 19 =
  35. 35.72 + 19 =
  36. 36.14 + 19 =
  37. 37.83 − 19 =
  38. 38.37 − 19 =
  39. 39.155 + 99 =
  40. 40.741 − 99 =

Answer key

  1. 58
  2. 46
  3. 75
  4. 53
  5. 82
  6. 5
  7. 26
  8. 243
  9. 24
  10. 37
  11. 48
  12. 88
  13. 60
  14. 84
  15. 38
  16. 29
  17. 106
  18. 599
  19. 77
  20. 47
  21. 240
  22. 95
  23. 69
  24. 677
  25. 273
  26. 54
  27. 31
  28. 66
  29. 711
  30. 27
  31. 12
  32. 57
  33. 45
  34. 98
  35. 91
  36. 33
  37. 64
  38. 18
  39. 254
  40. 642

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