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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 174 · 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. 1.442 + 99 =
  2. 2.39 + 9 =
  3. 3.76 + 9 =
  4. 4.39 + 19 =
  5. 5.37 + 9 =
  6. 6.58 − 29 =
  7. 7.35 + 29 =
  8. 8.71 − 29 =
  9. 9.80 − 29 =
  10. 10.87 − 29 =
  11. 11.428 − 99 =
  12. 12.27 + 9 =
  13. 13.58 − 9 =
  14. 14.25 − 19 =
  15. 15.57 + 9 =
  16. 16.95 − 19 =
  17. 17.44 − 19 =
  18. 18.25 + 29 =
  19. 19.32 + 9 =
  20. 20.575 − 99 =
  21. 21.109 − 29 =
  22. 22.25 − 9 =
  23. 23.107 − 29 =
  24. 24.44 + 9 =
  25. 25.50 − 29 =
  26. 26.30 − 19 =
  27. 27.12 + 29 =
  28. 28.56 − 19 =
  29. 29.724 − 99 =
  30. 30.20 + 19 =
  31. 31.99 − 19 =
  32. 32.192 + 99 =
  33. 33.76 + 29 =
  34. 34.426 − 99 =
  35. 35.63 − 9 =
  36. 36.36 + 9 =
  37. 37.14 + 9 =
  38. 38.54 + 9 =
  39. 39.69 + 9 =
  40. 40.84 − 9 =

Answer key

  1. 541
  2. 48
  3. 85
  4. 58
  5. 46
  6. 29
  7. 64
  8. 42
  9. 51
  10. 58
  11. 329
  12. 36
  13. 49
  14. 6
  15. 66
  16. 76
  17. 25
  18. 54
  19. 41
  20. 476
  21. 80
  22. 16
  23. 78
  24. 53
  25. 21
  26. 11
  27. 41
  28. 37
  29. 625
  30. 39
  31. 80
  32. 291
  33. 105
  34. 327
  35. 54
  36. 45
  37. 23
  38. 63
  39. 78
  40. 75

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