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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 19 · 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. 1.32 + 29 =
  2. 2.550 + 99 =
  3. 3.40 − 9 =
  4. 4.68 − 9 =
  5. 5.34 + 19 =
  6. 6.65 + 9 =
  7. 7.37 − 19 =
  8. 8.366 − 99 =
  9. 9.766 + 99 =
  10. 10.84 − 9 =
  11. 11.19 + 9 =
  12. 12.105 − 29 =
  13. 13.26 − 19 =
  14. 14.666 − 99 =
  15. 15.34 − 19 =
  16. 16.40 − 19 =
  17. 17.358 − 99 =
  18. 18.590 − 99 =
  19. 19.860 − 99 =
  20. 20.36 − 9 =
  21. 21.99 − 19 =
  22. 22.71 − 9 =
  23. 23.52 − 19 =
  24. 24.67 − 29 =
  25. 25.768 + 99 =
  26. 26.87 − 9 =
  27. 27.51 + 19 =
  28. 28.286 − 99 =
  29. 29.63 − 29 =
  30. 30.454 + 99 =
  31. 31.26 + 29 =
  32. 32.73 − 9 =
  33. 33.79 − 19 =
  34. 34.63 + 19 =
  35. 35.55 + 9 =
  36. 36.717 − 99 =
  37. 37.73 + 19 =
  38. 38.64 + 19 =
  39. 39.28 + 19 =
  40. 40.104 − 29 =

Answer key

  1. 61
  2. 649
  3. 31
  4. 59
  5. 53
  6. 74
  7. 18
  8. 267
  9. 865
  10. 75
  11. 28
  12. 76
  13. 7
  14. 567
  15. 15
  16. 21
  17. 259
  18. 491
  19. 761
  20. 27
  21. 80
  22. 62
  23. 33
  24. 38
  25. 867
  26. 78
  27. 70
  28. 187
  29. 34
  30. 553
  31. 55
  32. 64
  33. 60
  34. 82
  35. 64
  36. 618
  37. 92
  38. 83
  39. 47
  40. 75

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