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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 837 · 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. 1.273 + 99 =
  2. 2.474 − 99 =
  3. 3.70 + 19 =
  4. 4.56 − 9 =
  5. 5.64 + 9 =
  6. 6.109 − 29 =
  7. 7.65 + 9 =
  8. 8.356 + 99 =
  9. 9.30 − 19 =
  10. 10.115 + 99 =
  11. 11.34 + 9 =
  12. 12.85 − 19 =
  13. 13.58 + 9 =
  14. 14.492 − 99 =
  15. 15.37 − 9 =
  16. 16.56 + 19 =
  17. 17.620 + 99 =
  18. 18.40 + 19 =
  19. 19.20 + 19 =
  20. 20.69 − 9 =
  21. 21.67 + 9 =
  22. 22.24 + 29 =
  23. 23.44 − 19 =
  24. 24.53 + 19 =
  25. 25.36 − 19 =
  26. 26.79 − 9 =
  27. 27.546 + 99 =
  28. 28.79 + 9 =
  29. 29.76 + 9 =
  30. 30.26 + 19 =
  31. 31.48 − 29 =
  32. 32.15 + 19 =
  33. 33.378 + 99 =
  34. 34.48 + 29 =
  35. 35.34 − 9 =
  36. 36.68 − 19 =
  37. 37.683 − 99 =
  38. 38.29 − 9 =
  39. 39.65 − 29 =
  40. 40.773 + 99 =

Answer key

  1. 372
  2. 375
  3. 89
  4. 47
  5. 73
  6. 80
  7. 74
  8. 455
  9. 11
  10. 214
  11. 43
  12. 66
  13. 67
  14. 393
  15. 28
  16. 75
  17. 719
  18. 59
  19. 39
  20. 60
  21. 76
  22. 53
  23. 25
  24. 72
  25. 17
  26. 70
  27. 645
  28. 88
  29. 85
  30. 45
  31. 19
  32. 34
  33. 477
  34. 77
  35. 25
  36. 49
  37. 584
  38. 20
  39. 36
  40. 872

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