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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 468 · 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. 1.84 − 29 =
  2. 2.20 + 29 =
  3. 3.20 − 9 =
  4. 4.16 + 19 =
  5. 5.43 + 9 =
  6. 6.26 + 9 =
  7. 7.238 − 99 =
  8. 8.28 − 9 =
  9. 9.76 − 29 =
  10. 10.85 − 19 =
  11. 11.24 − 9 =
  12. 12.25 + 19 =
  13. 13.67 + 29 =
  14. 14.23 + 29 =
  15. 15.37 + 9 =
  16. 16.13 + 9 =
  17. 17.42 + 9 =
  18. 18.52 + 29 =
  19. 19.561 − 99 =
  20. 20.74 + 19 =
  21. 21.33 + 9 =
  22. 22.78 + 19 =
  23. 23.51 + 29 =
  24. 24.35 + 29 =
  25. 25.71 + 9 =
  26. 26.59 − 19 =
  27. 27.82 − 9 =
  28. 28.39 − 9 =
  29. 29.385 − 99 =
  30. 30.183 + 99 =
  31. 31.322 − 99 =
  32. 32.464 + 99 =
  33. 33.68 + 9 =
  34. 34.30 + 19 =
  35. 35.15 + 29 =
  36. 36.582 − 99 =
  37. 37.61 − 9 =
  38. 38.85 − 9 =
  39. 39.33 − 19 =
  40. 40.54 + 9 =

Answer key

  1. 55
  2. 49
  3. 11
  4. 35
  5. 52
  6. 35
  7. 139
  8. 19
  9. 47
  10. 66
  11. 15
  12. 44
  13. 96
  14. 52
  15. 46
  16. 22
  17. 51
  18. 81
  19. 462
  20. 93
  21. 42
  22. 97
  23. 80
  24. 64
  25. 80
  26. 40
  27. 73
  28. 30
  29. 286
  30. 282
  31. 223
  32. 563
  33. 77
  34. 49
  35. 44
  36. 483
  37. 52
  38. 76
  39. 14
  40. 63

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