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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 808 · 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 + 9 =
  2. 2.64 + 29 =
  3. 3.39 − 9 =
  4. 4.81 − 19 =
  5. 5.48 − 29 =
  6. 6.72 + 29 =
  7. 7.59 + 9 =
  8. 8.63 + 29 =
  9. 9.41 + 9 =
  10. 10.69 + 19 =
  11. 11.20 + 19 =
  12. 12.37 − 29 =
  13. 13.644 + 99 =
  14. 14.476 + 99 =
  15. 15.83 − 19 =
  16. 16.48 − 19 =
  17. 17.60 − 29 =
  18. 18.178 + 99 =
  19. 19.454 − 99 =
  20. 20.68 + 29 =
  21. 21.588 − 99 =
  22. 22.72 − 29 =
  23. 23.47 + 19 =
  24. 24.20 + 29 =
  25. 25.21 − 9 =
  26. 26.22 − 19 =
  27. 27.488 + 99 =
  28. 28.67 − 9 =
  29. 29.36 + 9 =
  30. 30.14 + 29 =
  31. 31.444 + 99 =
  32. 32.80 + 9 =
  33. 33.717 − 99 =
  34. 34.56 − 29 =
  35. 35.43 + 19 =
  36. 36.46 + 9 =
  37. 37.53 − 29 =
  38. 38.29 − 9 =
  39. 39.63 + 9 =
  40. 40.308 + 99 =

Answer key

  1. 61
  2. 93
  3. 30
  4. 62
  5. 19
  6. 101
  7. 68
  8. 92
  9. 50
  10. 88
  11. 39
  12. 8
  13. 743
  14. 575
  15. 64
  16. 29
  17. 31
  18. 277
  19. 355
  20. 97
  21. 489
  22. 43
  23. 66
  24. 49
  25. 12
  26. 3
  27. 587
  28. 58
  29. 45
  30. 43
  31. 543
  32. 89
  33. 618
  34. 27
  35. 62
  36. 55
  37. 24
  38. 20
  39. 72
  40. 407

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