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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 815 · 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. 1.66 + 9 =
  2. 2.714 + 99 =
  3. 3.31 + 29 =
  4. 4.46 − 9 =
  5. 5.33 − 9 =
  6. 6.16 − 9 =
  7. 7.76 + 19 =
  8. 8.61 − 19 =
  9. 9.59 + 9 =
  10. 10.69 − 19 =
  11. 11.87 − 9 =
  12. 12.70 + 29 =
  13. 13.222 − 99 =
  14. 14.50 + 9 =
  15. 15.36 + 9 =
  16. 16.73 − 19 =
  17. 17.175 + 99 =
  18. 18.33 − 29 =
  19. 19.475 − 99 =
  20. 20.35 + 29 =
  21. 21.116 + 99 =
  22. 22.15 − 9 =
  23. 23.40 + 19 =
  24. 24.485 − 99 =
  25. 25.27 + 29 =
  26. 26.223 + 99 =
  27. 27.15 + 19 =
  28. 28.185 + 99 =
  29. 29.47 + 19 =
  30. 30.39 + 19 =
  31. 31.32 − 19 =
  32. 32.62 − 29 =
  33. 33.13 + 29 =
  34. 34.760 − 99 =
  35. 35.18 + 29 =
  36. 36.723 − 99 =
  37. 37.63 + 19 =
  38. 38.19 + 29 =
  39. 39.413 − 99 =
  40. 40.226 + 99 =

Answer key

  1. 75
  2. 813
  3. 60
  4. 37
  5. 24
  6. 7
  7. 95
  8. 42
  9. 68
  10. 50
  11. 78
  12. 99
  13. 123
  14. 59
  15. 45
  16. 54
  17. 274
  18. 4
  19. 376
  20. 64
  21. 215
  22. 6
  23. 59
  24. 386
  25. 56
  26. 322
  27. 34
  28. 284
  29. 66
  30. 58
  31. 13
  32. 33
  33. 42
  34. 661
  35. 47
  36. 624
  37. 82
  38. 48
  39. 314
  40. 325

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