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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 860 · 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. 1.195 − 99 =
  2. 2.542 − 99 =
  3. 3.52 + 29 =
  4. 4.37 − 9 =
  5. 5.287 − 99 =
  6. 6.67 − 9 =
  7. 7.54 − 29 =
  8. 8.18 + 19 =
  9. 9.492 + 99 =
  10. 10.27 + 19 =
  11. 11.68 − 9 =
  12. 12.45 + 29 =
  13. 13.47 + 9 =
  14. 14.584 − 99 =
  15. 15.632 + 99 =
  16. 16.13 + 19 =
  17. 17.13 + 9 =
  18. 18.55 − 9 =
  19. 19.63 + 9 =
  20. 20.77 − 29 =
  21. 21.181 − 99 =
  22. 22.17 − 9 =
  23. 23.52 + 19 =
  24. 24.35 + 9 =
  25. 25.56 − 19 =
  26. 26.244 − 99 =
  27. 27.48 + 9 =
  28. 28.23 + 9 =
  29. 29.51 + 19 =
  30. 30.64 + 9 =
  31. 31.255 + 99 =
  32. 32.45 − 19 =
  33. 33.48 − 9 =
  34. 34.17 + 9 =
  35. 35.28 + 29 =
  36. 36.28 − 19 =
  37. 37.53 + 9 =
  38. 38.81 − 29 =
  39. 39.95 − 19 =
  40. 40.60 − 9 =

Answer key

  1. 96
  2. 443
  3. 81
  4. 28
  5. 188
  6. 58
  7. 25
  8. 37
  9. 591
  10. 46
  11. 59
  12. 74
  13. 56
  14. 485
  15. 731
  16. 32
  17. 22
  18. 46
  19. 72
  20. 48
  21. 82
  22. 8
  23. 71
  24. 44
  25. 37
  26. 145
  27. 57
  28. 32
  29. 70
  30. 73
  31. 354
  32. 26
  33. 39
  34. 26
  35. 57
  36. 9
  37. 62
  38. 52
  39. 76
  40. 51

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