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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 654 · 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. 1.73 − 9 =
  2. 2.27 + 19 =
  3. 3.15 + 29 =
  4. 4.749 + 99 =
  5. 5.71 + 29 =
  6. 6.18 + 19 =
  7. 7.33 − 19 =
  8. 8.34 − 9 =
  9. 9.23 − 9 =
  10. 10.695 − 99 =
  11. 11.419 − 99 =
  12. 12.69 − 9 =
  13. 13.47 − 9 =
  14. 14.900 − 99 =
  15. 15.53 − 9 =
  16. 16.45 − 29 =
  17. 17.614 − 99 =
  18. 18.25 + 9 =
  19. 19.32 − 19 =
  20. 20.20 + 29 =
  21. 21.75 − 9 =
  22. 22.107 + 99 =
  23. 23.64 + 9 =
  24. 24.104 − 29 =
  25. 25.38 + 9 =
  26. 26.30 − 9 =
  27. 27.66 − 29 =
  28. 28.334 + 99 =
  29. 29.35 − 19 =
  30. 30.199 − 99 =
  31. 31.25 + 29 =
  32. 32.82 − 9 =
  33. 33.60 + 19 =
  34. 34.522 + 99 =
  35. 35.40 − 19 =
  36. 36.175 + 99 =
  37. 37.70 − 29 =
  38. 38.33 + 19 =
  39. 39.75 + 19 =
  40. 40.30 − 19 =

Answer key

  1. 64
  2. 46
  3. 44
  4. 848
  5. 100
  6. 37
  7. 14
  8. 25
  9. 14
  10. 596
  11. 320
  12. 60
  13. 38
  14. 801
  15. 44
  16. 16
  17. 515
  18. 34
  19. 13
  20. 49
  21. 66
  22. 206
  23. 73
  24. 75
  25. 47
  26. 21
  27. 37
  28. 433
  29. 16
  30. 100
  31. 54
  32. 73
  33. 79
  34. 621
  35. 21
  36. 274
  37. 41
  38. 52
  39. 94
  40. 11

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