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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 812 · 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. 1.62 − 9 =
  2. 2.23 − 19 =
  3. 3.47 + 29 =
  4. 4.355 + 99 =
  5. 5.51 − 9 =
  6. 6.99 − 19 =
  7. 7.553 + 99 =
  8. 8.353 − 99 =
  9. 9.50 − 19 =
  10. 10.81 − 29 =
  11. 11.24 + 9 =
  12. 12.15 + 9 =
  13. 13.27 − 9 =
  14. 14.28 + 9 =
  15. 15.361 − 99 =
  16. 16.640 − 99 =
  17. 17.392 − 99 =
  18. 18.22 − 19 =
  19. 19.32 − 19 =
  20. 20.91 − 19 =
  21. 21.48 − 19 =
  22. 22.18 + 9 =
  23. 23.73 − 9 =
  24. 24.61 − 29 =
  25. 25.19 + 19 =
  26. 26.16 + 9 =
  27. 27.772 − 99 =
  28. 28.25 − 19 =
  29. 29.478 + 99 =
  30. 30.665 + 99 =
  31. 31.306 + 99 =
  32. 32.47 + 9 =
  33. 33.41 − 9 =
  34. 34.50 + 9 =
  35. 35.81 − 19 =
  36. 36.48 − 9 =
  37. 37.141 + 99 =
  38. 38.39 − 19 =
  39. 39.51 + 9 =
  40. 40.64 − 29 =

Answer key

  1. 53
  2. 4
  3. 76
  4. 454
  5. 42
  6. 80
  7. 652
  8. 254
  9. 31
  10. 52
  11. 33
  12. 24
  13. 18
  14. 37
  15. 262
  16. 541
  17. 293
  18. 3
  19. 13
  20. 72
  21. 29
  22. 27
  23. 64
  24. 32
  25. 38
  26. 25
  27. 673
  28. 6
  29. 577
  30. 764
  31. 405
  32. 56
  33. 32
  34. 59
  35. 62
  36. 39
  37. 240
  38. 20
  39. 60
  40. 35

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