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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 591 · 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. 1.26 − 19 =
  2. 2.46 + 29 =
  3. 3.38 + 29 =
  4. 4.19 + 9 =
  5. 5.99 − 19 =
  6. 6.24 − 19 =
  7. 7.73 + 19 =
  8. 8.73 − 9 =
  9. 9.40 − 19 =
  10. 10.88 − 29 =
  11. 11.29 + 29 =
  12. 12.62 − 9 =
  13. 13.41 − 29 =
  14. 14.12 + 9 =
  15. 15.44 + 29 =
  16. 16.60 − 19 =
  17. 17.28 − 9 =
  18. 18.49 + 19 =
  19. 19.59 + 29 =
  20. 20.69 − 9 =
  21. 21.59 − 29 =
  22. 22.45 − 9 =
  23. 23.34 + 29 =
  24. 24.69 + 19 =
  25. 25.39 − 19 =
  26. 26.105 − 29 =
  27. 27.841 − 99 =
  28. 28.51 + 29 =
  29. 29.69 + 29 =
  30. 30.77 + 9 =
  31. 31.297 + 99 =
  32. 32.229 + 99 =
  33. 33.14 + 29 =
  34. 34.14 + 19 =
  35. 35.871 − 99 =
  36. 36.56 − 19 =
  37. 37.24 + 29 =
  38. 38.76 − 9 =
  39. 39.51 − 29 =
  40. 40.34 − 9 =

Answer key

  1. 7
  2. 75
  3. 67
  4. 28
  5. 80
  6. 5
  7. 92
  8. 64
  9. 21
  10. 59
  11. 58
  12. 53
  13. 12
  14. 21
  15. 73
  16. 41
  17. 19
  18. 68
  19. 88
  20. 60
  21. 30
  22. 36
  23. 63
  24. 88
  25. 20
  26. 76
  27. 742
  28. 80
  29. 98
  30. 86
  31. 396
  32. 328
  33. 43
  34. 33
  35. 772
  36. 37
  37. 53
  38. 67
  39. 22
  40. 25

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