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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 795 · 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. 1.59 − 9 =
  2. 2.423 + 99 =
  3. 3.762 + 99 =
  4. 4.561 − 99 =
  5. 5.358 + 99 =
  6. 6.68 + 19 =
  7. 7.62 + 9 =
  8. 8.547 − 99 =
  9. 9.363 − 99 =
  10. 10.41 + 29 =
  11. 11.92 − 29 =
  12. 12.37 + 29 =
  13. 13.69 + 19 =
  14. 14.591 − 99 =
  15. 15.40 − 19 =
  16. 16.224 + 99 =
  17. 17.80 − 19 =
  18. 18.272 + 99 =
  19. 19.109 − 29 =
  20. 20.412 − 99 =
  21. 21.58 + 19 =
  22. 22.60 − 19 =
  23. 23.25 − 9 =
  24. 24.45 − 9 =
  25. 25.35 + 9 =
  26. 26.46 − 9 =
  27. 27.66 − 19 =
  28. 28.44 − 19 =
  29. 29.26 + 29 =
  30. 30.14 + 19 =
  31. 31.634 + 99 =
  32. 32.71 + 29 =
  33. 33.70 + 19 =
  34. 34.66 − 29 =
  35. 35.57 − 29 =
  36. 36.50 + 9 =
  37. 37.90 − 19 =
  38. 38.52 + 19 =
  39. 39.23 + 29 =
  40. 40.84 − 9 =

Answer key

  1. 50
  2. 522
  3. 861
  4. 462
  5. 457
  6. 87
  7. 71
  8. 448
  9. 264
  10. 70
  11. 63
  12. 66
  13. 88
  14. 492
  15. 21
  16. 323
  17. 61
  18. 371
  19. 80
  20. 313
  21. 77
  22. 41
  23. 16
  24. 36
  25. 44
  26. 37
  27. 47
  28. 25
  29. 55
  30. 33
  31. 733
  32. 100
  33. 89
  34. 37
  35. 28
  36. 59
  37. 71
  38. 71
  39. 52
  40. 75

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