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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 881 · 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. 1.33 + 19 =
  2. 2.25 + 29 =
  3. 3.61 − 19 =
  4. 4.316 − 99 =
  5. 5.21 − 9 =
  6. 6.37 + 9 =
  7. 7.27 + 29 =
  8. 8.95 − 29 =
  9. 9.79 − 29 =
  10. 10.58 − 29 =
  11. 11.460 + 99 =
  12. 12.70 + 9 =
  13. 13.50 + 9 =
  14. 14.28 + 29 =
  15. 15.176 + 99 =
  16. 16.73 − 19 =
  17. 17.80 − 19 =
  18. 18.14 − 9 =
  19. 19.77 + 29 =
  20. 20.345 + 99 =
  21. 21.42 − 29 =
  22. 22.297 − 99 =
  23. 23.28 + 9 =
  24. 24.643 + 99 =
  25. 25.38 − 9 =
  26. 26.92 − 19 =
  27. 27.25 − 9 =
  28. 28.83 − 29 =
  29. 29.34 − 19 =
  30. 30.63 − 19 =
  31. 31.106 + 99 =
  32. 32.41 + 9 =
  33. 33.631 − 99 =
  34. 34.468 − 99 =
  35. 35.46 − 9 =
  36. 36.37 − 29 =
  37. 37.56 + 29 =
  38. 38.19 − 9 =
  39. 39.773 − 99 =
  40. 40.72 − 29 =

Answer key

  1. 52
  2. 54
  3. 42
  4. 217
  5. 12
  6. 46
  7. 56
  8. 66
  9. 50
  10. 29
  11. 559
  12. 79
  13. 59
  14. 57
  15. 275
  16. 54
  17. 61
  18. 5
  19. 106
  20. 444
  21. 13
  22. 198
  23. 37
  24. 742
  25. 29
  26. 73
  27. 16
  28. 54
  29. 15
  30. 44
  31. 205
  32. 50
  33. 532
  34. 369
  35. 37
  36. 8
  37. 85
  38. 10
  39. 674
  40. 43

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