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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 533 · 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. 1.21 + 9 =
  2. 2.59 + 9 =
  3. 3.28 − 9 =
  4. 4.39 + 19 =
  5. 5.13 − 9 =
  6. 6.32 − 29 =
  7. 7.12 + 29 =
  8. 8.22 + 9 =
  9. 9.39 − 19 =
  10. 10.607 + 99 =
  11. 11.60 + 9 =
  12. 12.88 − 29 =
  13. 13.22 − 19 =
  14. 14.29 − 19 =
  15. 15.17 + 19 =
  16. 16.55 + 9 =
  17. 17.64 + 19 =
  18. 18.38 + 19 =
  19. 19.417 + 99 =
  20. 20.37 + 19 =
  21. 21.65 + 9 =
  22. 22.224 + 99 =
  23. 23.76 − 19 =
  24. 24.16 + 9 =
  25. 25.54 + 9 =
  26. 26.416 − 99 =
  27. 27.823 − 99 =
  28. 28.32 − 19 =
  29. 29.76 + 19 =
  30. 30.14 + 29 =
  31. 31.60 + 29 =
  32. 32.226 + 99 =
  33. 33.47 − 29 =
  34. 34.600 − 99 =
  35. 35.45 + 29 =
  36. 36.74 − 19 =
  37. 37.17 − 9 =
  38. 38.16 − 9 =
  39. 39.54 − 19 =
  40. 40.33 + 9 =

Answer key

  1. 30
  2. 68
  3. 19
  4. 58
  5. 4
  6. 3
  7. 41
  8. 31
  9. 20
  10. 706
  11. 69
  12. 59
  13. 3
  14. 10
  15. 36
  16. 64
  17. 83
  18. 57
  19. 516
  20. 56
  21. 74
  22. 323
  23. 57
  24. 25
  25. 63
  26. 317
  27. 724
  28. 13
  29. 95
  30. 43
  31. 89
  32. 325
  33. 18
  34. 501
  35. 74
  36. 55
  37. 8
  38. 7
  39. 35
  40. 42

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