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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 534 · 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. 1.43 + 9 =
  2. 2.44 + 29 =
  3. 3.65 + 9 =
  4. 4.36 − 19 =
  5. 5.46 − 9 =
  6. 6.40 − 19 =
  7. 7.88 − 29 =
  8. 8.672 + 99 =
  9. 9.409 − 99 =
  10. 10.15 − 9 =
  11. 11.28 + 9 =
  12. 12.80 + 9 =
  13. 13.93 − 19 =
  14. 14.77 − 19 =
  15. 15.14 + 9 =
  16. 16.81 − 19 =
  17. 17.23 + 19 =
  18. 18.19 + 9 =
  19. 19.47 + 29 =
  20. 20.72 − 9 =
  21. 21.65 + 29 =
  22. 22.19 − 9 =
  23. 23.49 + 19 =
  24. 24.27 + 9 =
  25. 25.19 + 19 =
  26. 26.46 + 19 =
  27. 27.30 + 19 =
  28. 28.36 + 9 =
  29. 29.84 − 9 =
  30. 30.36 − 9 =
  31. 31.43 + 29 =
  32. 32.94 − 29 =
  33. 33.215 − 99 =
  34. 34.65 − 9 =
  35. 35.28 + 29 =
  36. 36.53 − 29 =
  37. 37.690 + 99 =
  38. 38.122 + 99 =
  39. 39.17 + 19 =
  40. 40.798 + 99 =

Answer key

  1. 52
  2. 73
  3. 74
  4. 17
  5. 37
  6. 21
  7. 59
  8. 771
  9. 310
  10. 6
  11. 37
  12. 89
  13. 74
  14. 58
  15. 23
  16. 62
  17. 42
  18. 28
  19. 76
  20. 63
  21. 94
  22. 10
  23. 68
  24. 36
  25. 38
  26. 65
  27. 49
  28. 45
  29. 75
  30. 27
  31. 72
  32. 65
  33. 116
  34. 56
  35. 57
  36. 24
  37. 789
  38. 221
  39. 36
  40. 897

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