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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 203 · 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. 1.76 − 9 =
  2. 2.19 + 29 =
  3. 3.17 + 19 =
  4. 4.76 + 19 =
  5. 5.73 − 19 =
  6. 6.52 − 29 =
  7. 7.73 − 9 =
  8. 8.16 + 19 =
  9. 9.32 + 29 =
  10. 10.473 + 99 =
  11. 11.25 − 9 =
  12. 12.60 + 29 =
  13. 13.36 + 9 =
  14. 14.22 + 29 =
  15. 15.702 − 99 =
  16. 16.56 − 29 =
  17. 17.305 − 99 =
  18. 18.485 − 99 =
  19. 19.44 + 9 =
  20. 20.502 + 99 =
  21. 21.24 + 19 =
  22. 22.37 − 29 =
  23. 23.26 − 19 =
  24. 24.615 − 99 =
  25. 25.82 − 19 =
  26. 26.55 − 19 =
  27. 27.42 + 19 =
  28. 28.478 − 99 =
  29. 29.60 − 19 =
  30. 30.421 + 99 =
  31. 31.59 + 9 =
  32. 32.66 + 29 =
  33. 33.41 − 29 =
  34. 34.45 − 9 =
  35. 35.56 + 19 =
  36. 36.78 + 19 =
  37. 37.366 − 99 =
  38. 38.23 − 9 =
  39. 39.29 + 29 =
  40. 40.27 + 19 =

Answer key

  1. 67
  2. 48
  3. 36
  4. 95
  5. 54
  6. 23
  7. 64
  8. 35
  9. 61
  10. 572
  11. 16
  12. 89
  13. 45
  14. 51
  15. 603
  16. 27
  17. 206
  18. 386
  19. 53
  20. 601
  21. 43
  22. 8
  23. 7
  24. 516
  25. 63
  26. 36
  27. 61
  28. 379
  29. 41
  30. 520
  31. 68
  32. 95
  33. 12
  34. 36
  35. 75
  36. 97
  37. 267
  38. 14
  39. 58
  40. 46

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