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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 364 · 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. 1.543 − 99 =
  2. 2.630 − 99 =
  3. 3.26 + 19 =
  4. 4.38 + 9 =
  5. 5.43 − 19 =
  6. 6.25 + 9 =
  7. 7.740 − 99 =
  8. 8.120 + 99 =
  9. 9.33 − 19 =
  10. 10.68 − 29 =
  11. 11.13 + 19 =
  12. 12.70 + 9 =
  13. 13.29 + 9 =
  14. 14.245 + 99 =
  15. 15.19 + 29 =
  16. 16.53 − 9 =
  17. 17.25 − 19 =
  18. 18.76 + 19 =
  19. 19.83 − 9 =
  20. 20.63 − 19 =
  21. 21.84 − 29 =
  22. 22.86 − 29 =
  23. 23.45 − 29 =
  24. 24.772 + 99 =
  25. 25.34 + 9 =
  26. 26.293 − 99 =
  27. 27.22 + 29 =
  28. 28.22 + 19 =
  29. 29.68 + 19 =
  30. 30.24 + 29 =
  31. 31.55 − 29 =
  32. 32.275 + 99 =
  33. 33.473 + 99 =
  34. 34.33 + 9 =
  35. 35.842 − 99 =
  36. 36.364 − 99 =
  37. 37.24 − 19 =
  38. 38.22 − 9 =
  39. 39.214 − 99 =
  40. 40.72 − 9 =

Answer key

  1. 444
  2. 531
  3. 45
  4. 47
  5. 24
  6. 34
  7. 641
  8. 219
  9. 14
  10. 39
  11. 32
  12. 79
  13. 38
  14. 344
  15. 48
  16. 44
  17. 6
  18. 95
  19. 74
  20. 44
  21. 55
  22. 57
  23. 16
  24. 871
  25. 43
  26. 194
  27. 51
  28. 41
  29. 87
  30. 53
  31. 26
  32. 374
  33. 572
  34. 42
  35. 743
  36. 265
  37. 5
  38. 13
  39. 115
  40. 63

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