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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 907 · 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. 1.89 − 29 =
  2. 2.283 + 99 =
  3. 3.59 + 29 =
  4. 4.55 + 9 =
  5. 5.65 + 9 =
  6. 6.295 + 99 =
  7. 7.284 − 99 =
  8. 8.78 − 29 =
  9. 9.76 + 29 =
  10. 10.467 + 99 =
  11. 11.192 + 99 =
  12. 12.31 + 9 =
  13. 13.87 − 19 =
  14. 14.20 + 9 =
  15. 15.38 − 29 =
  16. 16.77 + 29 =
  17. 17.177 + 99 =
  18. 18.43 + 9 =
  19. 19.58 − 19 =
  20. 20.33 + 9 =
  21. 21.14 − 9 =
  22. 22.315 + 99 =
  23. 23.42 + 9 =
  24. 24.22 + 19 =
  25. 25.20 + 19 =
  26. 26.239 + 99 =
  27. 27.31 − 9 =
  28. 28.581 − 99 =
  29. 29.342 − 99 =
  30. 30.39 − 29 =
  31. 31.27 + 29 =
  32. 32.18 + 19 =
  33. 33.52 − 29 =
  34. 34.55 + 29 =
  35. 35.315 − 99 =
  36. 36.80 + 9 =
  37. 37.79 − 19 =
  38. 38.14 + 19 =
  39. 39.75 − 9 =
  40. 40.75 + 9 =

Answer key

  1. 60
  2. 382
  3. 88
  4. 64
  5. 74
  6. 394
  7. 185
  8. 49
  9. 105
  10. 566
  11. 291
  12. 40
  13. 68
  14. 29
  15. 9
  16. 106
  17. 276
  18. 52
  19. 39
  20. 42
  21. 5
  22. 414
  23. 51
  24. 41
  25. 39
  26. 338
  27. 22
  28. 482
  29. 243
  30. 10
  31. 56
  32. 37
  33. 23
  34. 84
  35. 216
  36. 89
  37. 60
  38. 33
  39. 66
  40. 84

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