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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 284 · 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. 1.24 − 19 =
  2. 2.57 − 19 =
  3. 3.25 + 19 =
  4. 4.13 + 19 =
  5. 5.49 + 9 =
  6. 6.23 + 9 =
  7. 7.84 − 19 =
  8. 8.75 − 29 =
  9. 9.77 + 19 =
  10. 10.25 + 9 =
  11. 11.67 + 19 =
  12. 12.41 − 29 =
  13. 13.202 + 99 =
  14. 14.68 + 19 =
  15. 15.48 − 29 =
  16. 16.50 + 19 =
  17. 17.14 + 29 =
  18. 18.38 − 19 =
  19. 19.303 + 99 =
  20. 20.44 − 9 =
  21. 21.32 − 29 =
  22. 22.291 − 99 =
  23. 23.47 + 29 =
  24. 24.80 + 9 =
  25. 25.51 − 9 =
  26. 26.63 + 9 =
  27. 27.20 + 9 =
  28. 28.75 + 9 =
  29. 29.85 − 9 =
  30. 30.791 + 99 =
  31. 31.592 − 99 =
  32. 32.62 − 19 =
  33. 33.747 + 99 =
  34. 34.41 + 9 =
  35. 35.34 − 29 =
  36. 36.42 + 19 =
  37. 37.322 − 99 =
  38. 38.42 − 29 =
  39. 39.338 + 99 =
  40. 40.42 + 29 =

Answer key

  1. 5
  2. 38
  3. 44
  4. 32
  5. 58
  6. 32
  7. 65
  8. 46
  9. 96
  10. 34
  11. 86
  12. 12
  13. 301
  14. 87
  15. 19
  16. 69
  17. 43
  18. 19
  19. 402
  20. 35
  21. 3
  22. 192
  23. 76
  24. 89
  25. 42
  26. 72
  27. 29
  28. 84
  29. 76
  30. 890
  31. 493
  32. 43
  33. 846
  34. 50
  35. 5
  36. 61
  37. 223
  38. 13
  39. 437
  40. 71

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