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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 348 · 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. 1.75 + 9 =
  2. 2.48 + 19 =
  3. 3.16 + 9 =
  4. 4.65 − 19 =
  5. 5.39 + 19 =
  6. 6.542 + 99 =
  7. 7.678 + 99 =
  8. 8.13 + 29 =
  9. 9.181 − 99 =
  10. 10.75 − 29 =
  11. 11.25 + 19 =
  12. 12.651 + 99 =
  13. 13.891 − 99 =
  14. 14.49 − 9 =
  15. 15.37 + 19 =
  16. 16.40 + 9 =
  17. 17.63 − 9 =
  18. 18.480 + 99 =
  19. 19.34 − 9 =
  20. 20.74 + 19 =
  21. 21.71 − 19 =
  22. 22.58 − 9 =
  23. 23.17 + 29 =
  24. 24.16 + 29 =
  25. 25.67 + 9 =
  26. 26.802 − 99 =
  27. 27.73 − 9 =
  28. 28.78 − 19 =
  29. 29.474 + 99 =
  30. 30.44 − 9 =
  31. 31.21 + 29 =
  32. 32.44 − 19 =
  33. 33.522 + 99 =
  34. 34.473 + 99 =
  35. 35.61 + 9 =
  36. 36.52 + 29 =
  37. 37.64 − 29 =
  38. 38.84 − 29 =
  39. 39.14 + 29 =
  40. 40.95 − 19 =

Answer key

  1. 84
  2. 67
  3. 25
  4. 46
  5. 58
  6. 641
  7. 777
  8. 42
  9. 82
  10. 46
  11. 44
  12. 750
  13. 792
  14. 40
  15. 56
  16. 49
  17. 54
  18. 579
  19. 25
  20. 93
  21. 52
  22. 49
  23. 46
  24. 45
  25. 76
  26. 703
  27. 64
  28. 59
  29. 573
  30. 35
  31. 50
  32. 25
  33. 621
  34. 572
  35. 70
  36. 81
  37. 35
  38. 55
  39. 43
  40. 76

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