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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 567 · 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. 1.28 + 29 =
  2. 2.24 + 19 =
  3. 3.54 − 29 =
  4. 4.17 − 9 =
  5. 5.25 − 9 =
  6. 6.14 + 29 =
  7. 7.243 − 99 =
  8. 8.102 − 29 =
  9. 9.537 + 99 =
  10. 10.13 + 19 =
  11. 11.71 + 9 =
  12. 12.316 − 99 =
  13. 13.33 − 19 =
  14. 14.45 + 29 =
  15. 15.18 − 9 =
  16. 16.86 − 19 =
  17. 17.21 − 9 =
  18. 18.41 − 29 =
  19. 19.76 + 9 =
  20. 20.29 + 29 =
  21. 21.16 + 9 =
  22. 22.40 + 19 =
  23. 23.57 − 29 =
  24. 24.159 + 99 =
  25. 25.25 + 29 =
  26. 26.724 + 99 =
  27. 27.73 + 19 =
  28. 28.103 − 29 =
  29. 29.42 − 29 =
  30. 30.51 + 19 =
  31. 31.281 − 99 =
  32. 32.35 + 9 =
  33. 33.526 + 99 =
  34. 34.432 + 99 =
  35. 35.722 + 99 =
  36. 36.69 − 29 =
  37. 37.43 − 29 =
  38. 38.53 + 9 =
  39. 39.310 − 99 =
  40. 40.42 + 9 =

Answer key

  1. 57
  2. 43
  3. 25
  4. 8
  5. 16
  6. 43
  7. 144
  8. 73
  9. 636
  10. 32
  11. 80
  12. 217
  13. 14
  14. 74
  15. 9
  16. 67
  17. 12
  18. 12
  19. 85
  20. 58
  21. 25
  22. 59
  23. 28
  24. 258
  25. 54
  26. 823
  27. 92
  28. 74
  29. 13
  30. 70
  31. 182
  32. 44
  33. 625
  34. 531
  35. 821
  36. 40
  37. 14
  38. 62
  39. 211
  40. 51

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