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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 547 · 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. 1.63 + 29 =
  2. 2.38 + 9 =
  3. 3.42 + 9 =
  4. 4.22 − 9 =
  5. 5.94 − 29 =
  6. 6.23 + 29 =
  7. 7.22 + 9 =
  8. 8.70 + 19 =
  9. 9.532 + 99 =
  10. 10.62 − 9 =
  11. 11.21 + 19 =
  12. 12.68 − 19 =
  13. 13.19 + 29 =
  14. 14.16 − 9 =
  15. 15.59 + 9 =
  16. 16.48 − 9 =
  17. 17.19 − 9 =
  18. 18.35 − 19 =
  19. 19.60 − 29 =
  20. 20.279 + 99 =
  21. 21.252 + 99 =
  22. 22.22 + 19 =
  23. 23.21 + 29 =
  24. 24.29 + 9 =
  25. 25.786 − 99 =
  26. 26.177 + 99 =
  27. 27.69 − 9 =
  28. 28.31 + 19 =
  29. 29.508 − 99 =
  30. 30.237 + 99 =
  31. 31.60 − 19 =
  32. 32.74 + 19 =
  33. 33.468 − 99 =
  34. 34.60 + 9 =
  35. 35.417 + 99 =
  36. 36.83 − 9 =
  37. 37.410 − 99 =
  38. 38.65 + 9 =
  39. 39.27 + 29 =
  40. 40.48 + 19 =

Answer key

  1. 92
  2. 47
  3. 51
  4. 13
  5. 65
  6. 52
  7. 31
  8. 89
  9. 631
  10. 53
  11. 40
  12. 49
  13. 48
  14. 7
  15. 68
  16. 39
  17. 10
  18. 16
  19. 31
  20. 378
  21. 351
  22. 41
  23. 50
  24. 38
  25. 687
  26. 276
  27. 60
  28. 50
  29. 409
  30. 336
  31. 41
  32. 93
  33. 369
  34. 69
  35. 516
  36. 74
  37. 311
  38. 74
  39. 56
  40. 67

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