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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 558 · 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. 1.14 + 19 =
  2. 2.20 − 9 =
  3. 3.133 + 99 =
  4. 4.27 − 19 =
  5. 5.22 + 19 =
  6. 6.39 + 19 =
  7. 7.71 + 19 =
  8. 8.45 + 29 =
  9. 9.62 − 29 =
  10. 10.16 + 9 =
  11. 11.21 + 19 =
  12. 12.19 + 29 =
  13. 13.25 + 29 =
  14. 14.18 − 9 =
  15. 15.42 − 19 =
  16. 16.23 − 9 =
  17. 17.59 − 9 =
  18. 18.90 − 29 =
  19. 19.17 − 9 =
  20. 20.78 − 9 =
  21. 21.94 − 19 =
  22. 22.76 + 29 =
  23. 23.80 − 9 =
  24. 24.79 − 29 =
  25. 25.31 − 19 =
  26. 26.28 − 19 =
  27. 27.36 + 9 =
  28. 28.63 − 9 =
  29. 29.89 − 9 =
  30. 30.16 + 29 =
  31. 31.219 + 99 =
  32. 32.39 − 9 =
  33. 33.33 + 19 =
  34. 34.88 − 19 =
  35. 35.41 + 9 =
  36. 36.13 − 9 =
  37. 37.12 + 29 =
  38. 38.95 − 19 =
  39. 39.74 − 19 =
  40. 40.869 − 99 =

Answer key

  1. 33
  2. 11
  3. 232
  4. 8
  5. 41
  6. 58
  7. 90
  8. 74
  9. 33
  10. 25
  11. 40
  12. 48
  13. 54
  14. 9
  15. 23
  16. 14
  17. 50
  18. 61
  19. 8
  20. 69
  21. 75
  22. 105
  23. 71
  24. 50
  25. 12
  26. 9
  27. 45
  28. 54
  29. 80
  30. 45
  31. 318
  32. 30
  33. 52
  34. 69
  35. 50
  36. 4
  37. 41
  38. 76
  39. 55
  40. 770

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