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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 40 · 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. 1.47 + 9 =
  2. 2.31 + 9 =
  3. 3.250 + 99 =
  4. 4.632 + 99 =
  5. 5.694 + 99 =
  6. 6.630 + 99 =
  7. 7.32 − 29 =
  8. 8.40 + 29 =
  9. 9.57 − 9 =
  10. 10.259 + 99 =
  11. 11.53 − 9 =
  12. 12.47 − 9 =
  13. 13.17 + 9 =
  14. 14.99 − 29 =
  15. 15.279 + 99 =
  16. 16.158 + 99 =
  17. 17.49 − 19 =
  18. 18.33 − 9 =
  19. 19.27 + 9 =
  20. 20.64 − 9 =
  21. 21.453 + 99 =
  22. 22.84 − 9 =
  23. 23.61 + 9 =
  24. 24.27 + 19 =
  25. 25.455 + 99 =
  26. 26.79 + 19 =
  27. 27.71 − 29 =
  28. 28.53 − 19 =
  29. 29.53 + 9 =
  30. 30.305 + 99 =
  31. 31.752 + 99 =
  32. 32.42 + 19 =
  33. 33.250 − 99 =
  34. 34.312 − 99 =
  35. 35.50 + 29 =
  36. 36.26 + 9 =
  37. 37.46 + 29 =
  38. 38.77 − 19 =
  39. 39.55 + 9 =
  40. 40.126 + 99 =

Answer key

  1. 56
  2. 40
  3. 349
  4. 731
  5. 793
  6. 729
  7. 3
  8. 69
  9. 48
  10. 358
  11. 44
  12. 38
  13. 26
  14. 70
  15. 378
  16. 257
  17. 30
  18. 24
  19. 36
  20. 55
  21. 552
  22. 75
  23. 70
  24. 46
  25. 554
  26. 98
  27. 42
  28. 34
  29. 62
  30. 404
  31. 851
  32. 61
  33. 151
  34. 213
  35. 79
  36. 35
  37. 75
  38. 58
  39. 64
  40. 225

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