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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 462 · 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. 1.52 + 19 =
  2. 2.35 + 19 =
  3. 3.27 − 19 =
  4. 4.18 + 29 =
  5. 5.18 − 9 =
  6. 6.241 + 99 =
  7. 7.69 + 9 =
  8. 8.50 − 9 =
  9. 9.623 − 99 =
  10. 10.74 − 29 =
  11. 11.12 + 29 =
  12. 12.74 + 19 =
  13. 13.760 + 99 =
  14. 14.36 − 9 =
  15. 15.442 − 99 =
  16. 16.109 − 29 =
  17. 17.43 + 29 =
  18. 18.41 + 29 =
  19. 19.66 + 9 =
  20. 20.564 + 99 =
  21. 21.15 + 29 =
  22. 22.46 − 29 =
  23. 23.80 + 29 =
  24. 24.36 + 9 =
  25. 25.755 − 99 =
  26. 26.55 − 29 =
  27. 27.747 + 99 =
  28. 28.79 + 19 =
  29. 29.53 − 9 =
  30. 30.57 − 29 =
  31. 31.235 + 99 =
  32. 32.245 − 99 =
  33. 33.73 + 19 =
  34. 34.78 + 19 =
  35. 35.41 + 9 =
  36. 36.78 + 9 =
  37. 37.73 + 9 =
  38. 38.88 − 9 =
  39. 39.34 − 19 =
  40. 40.618 − 99 =

Answer key

  1. 71
  2. 54
  3. 8
  4. 47
  5. 9
  6. 340
  7. 78
  8. 41
  9. 524
  10. 45
  11. 41
  12. 93
  13. 859
  14. 27
  15. 343
  16. 80
  17. 72
  18. 70
  19. 75
  20. 663
  21. 44
  22. 17
  23. 109
  24. 45
  25. 656
  26. 26
  27. 846
  28. 98
  29. 44
  30. 28
  31. 334
  32. 146
  33. 92
  34. 97
  35. 50
  36. 87
  37. 82
  38. 79
  39. 15
  40. 519

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