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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 477 · 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. 1.65 + 9 =
  2. 2.19 + 19 =
  3. 3.53 + 9 =
  4. 4.60 − 19 =
  5. 5.25 + 19 =
  6. 6.61 + 29 =
  7. 7.45 − 19 =
  8. 8.52 + 9 =
  9. 9.40 − 19 =
  10. 10.107 − 29 =
  11. 11.39 − 29 =
  12. 12.273 + 99 =
  13. 13.26 + 19 =
  14. 14.721 + 99 =
  15. 15.21 + 19 =
  16. 16.18 + 29 =
  17. 17.714 − 99 =
  18. 18.664 − 99 =
  19. 19.163 − 99 =
  20. 20.61 + 19 =
  21. 21.56 + 19 =
  22. 22.42 − 19 =
  23. 23.528 − 99 =
  24. 24.83 − 29 =
  25. 25.22 + 29 =
  26. 26.29 + 19 =
  27. 27.13 + 9 =
  28. 28.22 − 9 =
  29. 29.40 + 9 =
  30. 30.46 − 19 =
  31. 31.33 + 9 =
  32. 32.151 + 99 =
  33. 33.78 + 29 =
  34. 34.65 − 29 =
  35. 35.36 + 19 =
  36. 36.19 + 9 =
  37. 37.240 + 99 =
  38. 38.17 + 9 =
  39. 39.58 + 19 =
  40. 40.170 + 99 =

Answer key

  1. 74
  2. 38
  3. 62
  4. 41
  5. 44
  6. 90
  7. 26
  8. 61
  9. 21
  10. 78
  11. 10
  12. 372
  13. 45
  14. 820
  15. 40
  16. 47
  17. 615
  18. 565
  19. 64
  20. 80
  21. 75
  22. 23
  23. 429
  24. 54
  25. 51
  26. 48
  27. 22
  28. 13
  29. 49
  30. 27
  31. 42
  32. 250
  33. 107
  34. 36
  35. 55
  36. 28
  37. 339
  38. 26
  39. 77
  40. 269

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