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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 312 · 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. 1.189 + 99 =
  2. 2.66 − 19 =
  3. 3.44 + 19 =
  4. 4.42 + 9 =
  5. 5.737 − 99 =
  6. 6.59 − 29 =
  7. 7.60 − 19 =
  8. 8.16 − 9 =
  9. 9.31 + 9 =
  10. 10.41 − 19 =
  11. 11.73 − 19 =
  12. 12.78 + 29 =
  13. 13.63 − 9 =
  14. 14.87 − 9 =
  15. 15.366 − 99 =
  16. 16.28 + 9 =
  17. 17.70 − 29 =
  18. 18.15 + 9 =
  19. 19.72 − 29 =
  20. 20.13 + 9 =
  21. 21.597 − 99 =
  22. 22.302 + 99 =
  23. 23.531 + 99 =
  24. 24.900 − 99 =
  25. 25.40 − 9 =
  26. 26.67 + 19 =
  27. 27.110 + 99 =
  28. 28.35 − 9 =
  29. 29.163 − 99 =
  30. 30.732 + 99 =
  31. 31.875 − 99 =
  32. 32.38 − 9 =
  33. 33.12 + 9 =
  34. 34.26 − 9 =
  35. 35.883 − 99 =
  36. 36.839 − 99 =
  37. 37.29 − 9 =
  38. 38.203 + 99 =
  39. 39.458 − 99 =
  40. 40.13 + 19 =

Answer key

  1. 288
  2. 47
  3. 63
  4. 51
  5. 638
  6. 30
  7. 41
  8. 7
  9. 40
  10. 22
  11. 54
  12. 107
  13. 54
  14. 78
  15. 267
  16. 37
  17. 41
  18. 24
  19. 43
  20. 22
  21. 498
  22. 401
  23. 630
  24. 801
  25. 31
  26. 86
  27. 209
  28. 26
  29. 64
  30. 831
  31. 776
  32. 29
  33. 21
  34. 17
  35. 784
  36. 740
  37. 20
  38. 302
  39. 359
  40. 32

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