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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 213 · 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. 1.27 + 19 =
  2. 2.71 − 29 =
  3. 3.44 − 9 =
  4. 4.566 − 99 =
  5. 5.38 − 19 =
  6. 6.73 − 9 =
  7. 7.36 + 9 =
  8. 8.74 − 19 =
  9. 9.68 + 19 =
  10. 10.54 − 9 =
  11. 11.37 + 19 =
  12. 12.99 − 19 =
  13. 13.69 − 29 =
  14. 14.27 + 9 =
  15. 15.14 + 19 =
  16. 16.56 + 19 =
  17. 17.87 − 29 =
  18. 18.380 + 99 =
  19. 19.64 + 29 =
  20. 20.23 + 29 =
  21. 21.73 + 9 =
  22. 22.773 − 99 =
  23. 23.102 − 29 =
  24. 24.574 + 99 =
  25. 25.567 + 99 =
  26. 26.641 − 99 =
  27. 27.50 − 19 =
  28. 28.27 − 19 =
  29. 29.63 + 19 =
  30. 30.71 + 9 =
  31. 31.77 − 19 =
  32. 32.17 + 29 =
  33. 33.67 + 9 =
  34. 34.217 + 99 =
  35. 35.75 − 19 =
  36. 36.186 − 99 =
  37. 37.22 − 9 =
  38. 38.66 + 9 =
  39. 39.14 + 9 =
  40. 40.53 − 19 =

Answer key

  1. 46
  2. 42
  3. 35
  4. 467
  5. 19
  6. 64
  7. 45
  8. 55
  9. 87
  10. 45
  11. 56
  12. 80
  13. 40
  14. 36
  15. 33
  16. 75
  17. 58
  18. 479
  19. 93
  20. 52
  21. 82
  22. 674
  23. 73
  24. 673
  25. 666
  26. 542
  27. 31
  28. 8
  29. 82
  30. 80
  31. 58
  32. 46
  33. 76
  34. 316
  35. 56
  36. 87
  37. 13
  38. 75
  39. 23
  40. 34

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