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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 355 · 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. 1.22 − 9 =
  2. 2.85 − 9 =
  3. 3.75 + 9 =
  4. 4.15 + 9 =
  5. 5.22 + 19 =
  6. 6.21 + 29 =
  7. 7.27 + 9 =
  8. 8.63 − 9 =
  9. 9.17 + 19 =
  10. 10.158 + 99 =
  11. 11.45 − 29 =
  12. 12.31 + 9 =
  13. 13.434 − 99 =
  14. 14.76 − 19 =
  15. 15.48 + 29 =
  16. 16.498 − 99 =
  17. 17.755 − 99 =
  18. 18.12 − 9 =
  19. 19.64 + 9 =
  20. 20.51 − 29 =
  21. 21.35 − 9 =
  22. 22.17 + 9 =
  23. 23.70 + 9 =
  24. 24.743 + 99 =
  25. 25.46 − 19 =
  26. 26.71 + 29 =
  27. 27.19 + 29 =
  28. 28.746 − 99 =
  29. 29.64 − 9 =
  30. 30.34 − 19 =
  31. 31.23 + 29 =
  32. 32.581 + 99 =
  33. 33.39 − 19 =
  34. 34.48 − 29 =
  35. 35.75 + 19 =
  36. 36.637 + 99 =
  37. 37.493 + 99 =
  38. 38.181 − 99 =
  39. 39.47 + 29 =
  40. 40.41 − 29 =

Answer key

  1. 13
  2. 76
  3. 84
  4. 24
  5. 41
  6. 50
  7. 36
  8. 54
  9. 36
  10. 257
  11. 16
  12. 40
  13. 335
  14. 57
  15. 77
  16. 399
  17. 656
  18. 3
  19. 73
  20. 22
  21. 26
  22. 26
  23. 79
  24. 842
  25. 27
  26. 100
  27. 48
  28. 647
  29. 55
  30. 15
  31. 52
  32. 680
  33. 20
  34. 19
  35. 94
  36. 736
  37. 592
  38. 82
  39. 76
  40. 12

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