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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 270 · 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. 1.25 + 29 =
  2. 2.45 + 29 =
  3. 3.71 + 19 =
  4. 4.81 − 19 =
  5. 5.28 + 9 =
  6. 6.60 + 29 =
  7. 7.272 + 99 =
  8. 8.64 + 29 =
  9. 9.35 − 29 =
  10. 10.47 + 9 =
  11. 11.91 − 19 =
  12. 12.271 − 99 =
  13. 13.34 + 19 =
  14. 14.77 − 29 =
  15. 15.38 − 19 =
  16. 16.56 + 9 =
  17. 17.80 + 19 =
  18. 18.65 + 9 =
  19. 19.69 + 9 =
  20. 20.28 + 29 =
  21. 21.59 − 29 =
  22. 22.657 − 99 =
  23. 23.46 − 19 =
  24. 24.20 − 9 =
  25. 25.31 + 9 =
  26. 26.28 + 19 =
  27. 27.202 + 99 =
  28. 28.65 + 29 =
  29. 29.79 − 9 =
  30. 30.79 − 29 =
  31. 31.64 + 9 =
  32. 32.598 + 99 =
  33. 33.37 − 29 =
  34. 34.33 − 29 =
  35. 35.88 − 19 =
  36. 36.71 − 19 =
  37. 37.16 + 9 =
  38. 38.76 + 9 =
  39. 39.29 + 9 =
  40. 40.15 − 9 =

Answer key

  1. 54
  2. 74
  3. 90
  4. 62
  5. 37
  6. 89
  7. 371
  8. 93
  9. 6
  10. 56
  11. 72
  12. 172
  13. 53
  14. 48
  15. 19
  16. 65
  17. 99
  18. 74
  19. 78
  20. 57
  21. 30
  22. 558
  23. 27
  24. 11
  25. 40
  26. 47
  27. 301
  28. 94
  29. 70
  30. 50
  31. 73
  32. 697
  33. 8
  34. 4
  35. 69
  36. 52
  37. 25
  38. 85
  39. 38
  40. 6

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