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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 280 · 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. 1.41 − 19 =
  2. 2.23 + 9 =
  3. 3.29 − 9 =
  4. 4.95 − 29 =
  5. 5.404 + 99 =
  6. 6.64 − 19 =
  7. 7.62 − 19 =
  8. 8.45 + 9 =
  9. 9.253 + 99 =
  10. 10.78 − 9 =
  11. 11.26 − 19 =
  12. 12.305 − 99 =
  13. 13.20 − 9 =
  14. 14.40 − 29 =
  15. 15.46 + 9 =
  16. 16.60 + 9 =
  17. 17.28 − 9 =
  18. 18.49 + 19 =
  19. 19.40 + 29 =
  20. 20.800 − 99 =
  21. 21.300 + 99 =
  22. 22.33 + 19 =
  23. 23.18 + 29 =
  24. 24.38 + 29 =
  25. 25.273 + 99 =
  26. 26.27 + 29 =
  27. 27.599 − 99 =
  28. 28.89 − 19 =
  29. 29.729 − 99 =
  30. 30.70 + 29 =
  31. 31.74 + 9 =
  32. 32.96 − 29 =
  33. 33.48 − 29 =
  34. 34.58 − 9 =
  35. 35.41 + 29 =
  36. 36.58 + 9 =
  37. 37.77 + 19 =
  38. 38.35 − 19 =
  39. 39.764 + 99 =
  40. 40.63 + 9 =

Answer key

  1. 22
  2. 32
  3. 20
  4. 66
  5. 503
  6. 45
  7. 43
  8. 54
  9. 352
  10. 69
  11. 7
  12. 206
  13. 11
  14. 11
  15. 55
  16. 69
  17. 19
  18. 68
  19. 69
  20. 701
  21. 399
  22. 52
  23. 47
  24. 67
  25. 372
  26. 56
  27. 500
  28. 70
  29. 630
  30. 99
  31. 83
  32. 67
  33. 19
  34. 49
  35. 70
  36. 67
  37. 96
  38. 16
  39. 863
  40. 72

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