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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 417 · 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. 1.85 − 29 =
  2. 2.105 − 29 =
  3. 3.45 + 29 =
  4. 4.41 − 19 =
  5. 5.16 + 19 =
  6. 6.52 − 19 =
  7. 7.75 + 9 =
  8. 8.63 − 19 =
  9. 9.66 + 19 =
  10. 10.17 − 9 =
  11. 11.87 − 19 =
  12. 12.31 − 9 =
  13. 13.50 − 9 =
  14. 14.577 + 99 =
  15. 15.64 + 29 =
  16. 16.56 − 9 =
  17. 17.333 + 99 =
  18. 18.178 + 99 =
  19. 19.47 + 9 =
  20. 20.80 + 19 =
  21. 21.87 − 9 =
  22. 22.23 − 19 =
  23. 23.45 − 19 =
  24. 24.16 + 9 =
  25. 25.50 + 19 =
  26. 26.54 + 29 =
  27. 27.77 + 9 =
  28. 28.94 − 29 =
  29. 29.534 + 99 =
  30. 30.402 + 99 =
  31. 31.98 − 29 =
  32. 32.27 + 29 =
  33. 33.36 + 29 =
  34. 34.25 + 29 =
  35. 35.26 + 9 =
  36. 36.794 + 99 =
  37. 37.72 − 9 =
  38. 38.783 + 99 =
  39. 39.46 − 9 =
  40. 40.20 + 9 =

Answer key

  1. 56
  2. 76
  3. 74
  4. 22
  5. 35
  6. 33
  7. 84
  8. 44
  9. 85
  10. 8
  11. 68
  12. 22
  13. 41
  14. 676
  15. 93
  16. 47
  17. 432
  18. 277
  19. 56
  20. 99
  21. 78
  22. 4
  23. 26
  24. 25
  25. 69
  26. 83
  27. 86
  28. 65
  29. 633
  30. 501
  31. 69
  32. 56
  33. 65
  34. 54
  35. 35
  36. 893
  37. 63
  38. 882
  39. 37
  40. 29

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