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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 965 · 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. 1.32 + 9 =
  2. 2.45 − 19 =
  3. 3.55 + 9 =
  4. 4.60 + 29 =
  5. 5.53 + 9 =
  6. 6.77 − 9 =
  7. 7.88 − 9 =
  8. 8.80 − 29 =
  9. 9.23 + 9 =
  10. 10.49 + 9 =
  11. 11.50 − 9 =
  12. 12.72 − 19 =
  13. 13.83 − 9 =
  14. 14.54 + 29 =
  15. 15.35 + 9 =
  16. 16.58 + 9 =
  17. 17.63 − 19 =
  18. 18.269 + 99 =
  19. 19.25 − 9 =
  20. 20.67 − 9 =
  21. 21.43 − 19 =
  22. 22.19 + 9 =
  23. 23.501 + 99 =
  24. 24.18 − 9 =
  25. 25.52 − 19 =
  26. 26.78 + 9 =
  27. 27.53 + 19 =
  28. 28.54 − 19 =
  29. 29.14 + 29 =
  30. 30.42 − 9 =
  31. 31.206 − 99 =
  32. 32.40 + 9 =
  33. 33.330 − 99 =
  34. 34.28 − 19 =
  35. 35.631 − 99 =
  36. 36.54 + 19 =
  37. 37.60 + 19 =
  38. 38.298 + 99 =
  39. 39.24 + 19 =
  40. 40.43 + 9 =

Answer key

  1. 41
  2. 26
  3. 64
  4. 89
  5. 62
  6. 68
  7. 79
  8. 51
  9. 32
  10. 58
  11. 41
  12. 53
  13. 74
  14. 83
  15. 44
  16. 67
  17. 44
  18. 368
  19. 16
  20. 58
  21. 24
  22. 28
  23. 600
  24. 9
  25. 33
  26. 87
  27. 72
  28. 35
  29. 43
  30. 33
  31. 107
  32. 49
  33. 231
  34. 9
  35. 532
  36. 73
  37. 79
  38. 397
  39. 43
  40. 52

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