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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 994 · 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. 1.571 + 99 =
  2. 2.28 + 29 =
  3. 3.59 + 29 =
  4. 4.22 − 9 =
  5. 5.22 − 19 =
  6. 6.18 + 9 =
  7. 7.62 + 9 =
  8. 8.68 − 19 =
  9. 9.507 + 99 =
  10. 10.75 − 9 =
  11. 11.19 + 19 =
  12. 12.61 + 9 =
  13. 13.73 + 19 =
  14. 14.362 − 99 =
  15. 15.85 − 19 =
  16. 16.30 − 19 =
  17. 17.48 − 19 =
  18. 18.43 + 9 =
  19. 19.65 − 29 =
  20. 20.28 − 19 =
  21. 21.323 − 99 =
  22. 22.25 + 29 =
  23. 23.23 + 9 =
  24. 24.479 − 99 =
  25. 25.25 + 9 =
  26. 26.58 + 19 =
  27. 27.183 − 99 =
  28. 28.49 − 19 =
  29. 29.79 − 29 =
  30. 30.73 + 9 =
  31. 31.19 + 9 =
  32. 32.72 + 29 =
  33. 33.75 + 29 =
  34. 34.24 − 9 =
  35. 35.465 − 99 =
  36. 36.35 − 19 =
  37. 37.37 − 29 =
  38. 38.539 + 99 =
  39. 39.53 + 29 =
  40. 40.74 − 9 =

Answer key

  1. 670
  2. 57
  3. 88
  4. 13
  5. 3
  6. 27
  7. 71
  8. 49
  9. 606
  10. 66
  11. 38
  12. 70
  13. 92
  14. 263
  15. 66
  16. 11
  17. 29
  18. 52
  19. 36
  20. 9
  21. 224
  22. 54
  23. 32
  24. 380
  25. 34
  26. 77
  27. 84
  28. 30
  29. 50
  30. 82
  31. 28
  32. 101
  33. 104
  34. 15
  35. 366
  36. 16
  37. 8
  38. 638
  39. 82
  40. 65

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