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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 891 · 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. 1.67 − 29 =
  2. 2.207 − 99 =
  3. 3.43 + 19 =
  4. 4.80 + 19 =
  5. 5.257 + 99 =
  6. 6.45 − 19 =
  7. 7.83 − 19 =
  8. 8.798 + 99 =
  9. 9.24 − 19 =
  10. 10.332 − 99 =
  11. 11.160 − 99 =
  12. 12.65 + 29 =
  13. 13.593 + 99 =
  14. 14.710 − 99 =
  15. 15.578 + 99 =
  16. 16.12 + 9 =
  17. 17.400 + 99 =
  18. 18.19 + 29 =
  19. 19.31 + 19 =
  20. 20.43 − 19 =
  21. 21.54 − 19 =
  22. 22.497 + 99 =
  23. 23.44 − 29 =
  24. 24.12 + 29 =
  25. 25.41 − 19 =
  26. 26.16 + 9 =
  27. 27.43 − 29 =
  28. 28.543 + 99 =
  29. 29.105 − 29 =
  30. 30.40 + 29 =
  31. 31.741 − 99 =
  32. 32.15 + 9 =
  33. 33.27 + 29 =
  34. 34.77 − 29 =
  35. 35.281 − 99 =
  36. 36.47 + 29 =
  37. 37.36 + 9 =
  38. 38.42 − 29 =
  39. 39.93 − 29 =
  40. 40.23 + 29 =

Answer key

  1. 38
  2. 108
  3. 62
  4. 99
  5. 356
  6. 26
  7. 64
  8. 897
  9. 5
  10. 233
  11. 61
  12. 94
  13. 692
  14. 611
  15. 677
  16. 21
  17. 499
  18. 48
  19. 50
  20. 24
  21. 35
  22. 596
  23. 15
  24. 41
  25. 22
  26. 25
  27. 14
  28. 642
  29. 76
  30. 69
  31. 642
  32. 24
  33. 56
  34. 48
  35. 182
  36. 76
  37. 45
  38. 13
  39. 64
  40. 52

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