← Add and take away 9, 19 and 99 lesson New set →

Adding 9, 19 and 99 Mental Maths Worksheet

Mental maths lesson 4: Add and take away 9, 19 and 99 · Set 374 · 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. 1.668 − 99 =
  2. 2.720 − 99 =
  3. 3.90 − 19 =
  4. 4.13 + 9 =
  5. 5.601 − 99 =
  6. 6.186 + 99 =
  7. 7.437 + 99 =
  8. 8.447 − 99 =
  9. 9.40 − 29 =
  10. 10.15 + 29 =
  11. 11.58 + 29 =
  12. 12.42 + 29 =
  13. 13.57 − 19 =
  14. 14.27 − 9 =
  15. 15.65 + 29 =
  16. 16.29 − 9 =
  17. 17.31 + 19 =
  18. 18.50 − 9 =
  19. 19.45 + 9 =
  20. 20.82 − 29 =
  21. 21.16 + 29 =
  22. 22.40 + 9 =
  23. 23.46 + 29 =
  24. 24.687 − 99 =
  25. 25.56 − 19 =
  26. 26.34 − 19 =
  27. 27.19 + 29 =
  28. 28.65 + 9 =
  29. 29.78 + 19 =
  30. 30.169 − 99 =
  31. 31.79 − 19 =
  32. 32.24 + 9 =
  33. 33.37 + 9 =
  34. 34.19 − 9 =
  35. 35.36 + 19 =
  36. 36.67 + 9 =
  37. 37.305 − 99 =
  38. 38.38 + 29 =
  39. 39.446 + 99 =
  40. 40.423 − 99 =

Answer key

  1. 569
  2. 621
  3. 71
  4. 22
  5. 502
  6. 285
  7. 536
  8. 348
  9. 11
  10. 44
  11. 87
  12. 71
  13. 38
  14. 18
  15. 94
  16. 20
  17. 50
  18. 41
  19. 54
  20. 53
  21. 45
  22. 49
  23. 75
  24. 588
  25. 37
  26. 15
  27. 48
  28. 74
  29. 97
  30. 70
  31. 60
  32. 33
  33. 46
  34. 10
  35. 55
  36. 76
  37. 206
  38. 67
  39. 545
  40. 324

Free mental maths lessons, practice and worksheets at talentjr.in/mental-maths