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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 230 · 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. 1.224 + 99 =
  2. 2.36 + 19 =
  3. 3.21 + 29 =
  4. 4.15 + 29 =
  5. 5.26 + 19 =
  6. 6.33 + 9 =
  7. 7.87 − 29 =
  8. 8.71 + 19 =
  9. 9.63 − 9 =
  10. 10.76 − 19 =
  11. 11.605 − 99 =
  12. 12.74 + 29 =
  13. 13.30 + 19 =
  14. 14.13 + 9 =
  15. 15.30 − 19 =
  16. 16.202 − 99 =
  17. 17.47 − 29 =
  18. 18.53 − 19 =
  19. 19.213 − 99 =
  20. 20.30 + 9 =
  21. 21.561 − 99 =
  22. 22.44 + 9 =
  23. 23.68 − 9 =
  24. 24.17 + 19 =
  25. 25.62 − 29 =
  26. 26.223 + 99 =
  27. 27.673 + 99 =
  28. 28.32 + 19 =
  29. 29.52 − 19 =
  30. 30.50 − 9 =
  31. 31.41 − 29 =
  32. 32.295 + 99 =
  33. 33.44 + 19 =
  34. 34.739 + 99 =
  35. 35.27 − 9 =
  36. 36.468 + 99 =
  37. 37.52 + 9 =
  38. 38.64 + 9 =
  39. 39.53 − 9 =
  40. 40.546 + 99 =

Answer key

  1. 323
  2. 55
  3. 50
  4. 44
  5. 45
  6. 42
  7. 58
  8. 90
  9. 54
  10. 57
  11. 506
  12. 103
  13. 49
  14. 22
  15. 11
  16. 103
  17. 18
  18. 34
  19. 114
  20. 39
  21. 462
  22. 53
  23. 59
  24. 36
  25. 33
  26. 322
  27. 772
  28. 51
  29. 33
  30. 41
  31. 12
  32. 394
  33. 63
  34. 838
  35. 18
  36. 567
  37. 61
  38. 73
  39. 44
  40. 645

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