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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 502 · 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. 1.79 − 9 =
  2. 2.45 − 19 =
  3. 3.85 − 19 =
  4. 4.58 + 9 =
  5. 5.331 + 99 =
  6. 6.234 − 99 =
  7. 7.73 + 9 =
  8. 8.72 + 29 =
  9. 9.33 + 19 =
  10. 10.16 + 9 =
  11. 11.28 + 9 =
  12. 12.49 − 9 =
  13. 13.44 + 9 =
  14. 14.99 − 19 =
  15. 15.79 − 19 =
  16. 16.208 − 99 =
  17. 17.13 + 9 =
  18. 18.46 − 29 =
  19. 19.240 − 99 =
  20. 20.41 + 9 =
  21. 21.72 − 9 =
  22. 22.48 − 9 =
  23. 23.64 + 19 =
  24. 24.75 + 9 =
  25. 25.26 + 29 =
  26. 26.65 + 9 =
  27. 27.72 − 29 =
  28. 28.74 − 29 =
  29. 29.19 − 9 =
  30. 30.31 − 9 =
  31. 31.14 + 19 =
  32. 32.80 − 19 =
  33. 33.18 + 29 =
  34. 34.682 + 99 =
  35. 35.63 + 9 =
  36. 36.24 + 19 =
  37. 37.61 − 9 =
  38. 38.54 + 9 =
  39. 39.125 + 99 =
  40. 40.89 − 19 =

Answer key

  1. 70
  2. 26
  3. 66
  4. 67
  5. 430
  6. 135
  7. 82
  8. 101
  9. 52
  10. 25
  11. 37
  12. 40
  13. 53
  14. 80
  15. 60
  16. 109
  17. 22
  18. 17
  19. 141
  20. 50
  21. 63
  22. 39
  23. 83
  24. 84
  25. 55
  26. 74
  27. 43
  28. 45
  29. 10
  30. 22
  31. 33
  32. 61
  33. 47
  34. 781
  35. 72
  36. 43
  37. 52
  38. 63
  39. 224
  40. 70

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