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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 596 · 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. 1.73 + 19 =
  2. 2.34 + 19 =
  3. 3.72 + 9 =
  4. 4.495 + 99 =
  5. 5.205 + 99 =
  6. 6.31 − 19 =
  7. 7.71 − 9 =
  8. 8.22 + 19 =
  9. 9.44 − 19 =
  10. 10.40 + 19 =
  11. 11.68 − 9 =
  12. 12.83 − 29 =
  13. 13.586 − 99 =
  14. 14.17 + 29 =
  15. 15.54 − 19 =
  16. 16.135 + 99 =
  17. 17.223 − 99 =
  18. 18.384 − 99 =
  19. 19.28 + 29 =
  20. 20.561 + 99 =
  21. 21.89 − 29 =
  22. 22.32 − 9 =
  23. 23.93 − 19 =
  24. 24.79 − 29 =
  25. 25.847 − 99 =
  26. 26.80 + 19 =
  27. 27.280 − 99 =
  28. 28.45 − 9 =
  29. 29.68 + 9 =
  30. 30.19 + 9 =
  31. 31.37 − 9 =
  32. 32.49 − 19 =
  33. 33.61 + 29 =
  34. 34.608 + 99 =
  35. 35.97 − 19 =
  36. 36.18 + 19 =
  37. 37.31 + 9 =
  38. 38.44 − 9 =
  39. 39.292 + 99 =
  40. 40.71 + 19 =

Answer key

  1. 92
  2. 53
  3. 81
  4. 594
  5. 304
  6. 12
  7. 62
  8. 41
  9. 25
  10. 59
  11. 59
  12. 54
  13. 487
  14. 46
  15. 35
  16. 234
  17. 124
  18. 285
  19. 57
  20. 660
  21. 60
  22. 23
  23. 74
  24. 50
  25. 748
  26. 99
  27. 181
  28. 36
  29. 77
  30. 28
  31. 28
  32. 30
  33. 90
  34. 707
  35. 78
  36. 37
  37. 40
  38. 35
  39. 391
  40. 90

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