← 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 993 · 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. 1.31 + 9 =
  2. 2.79 − 29 =
  3. 3.311 + 99 =
  4. 4.96 − 19 =
  5. 5.79 + 29 =
  6. 6.47 − 9 =
  7. 7.73 + 29 =
  8. 8.78 − 9 =
  9. 9.522 + 99 =
  10. 10.48 + 29 =
  11. 11.60 + 29 =
  12. 12.24 + 19 =
  13. 13.15 + 19 =
  14. 14.41 + 9 =
  15. 15.19 + 29 =
  16. 16.85 − 29 =
  17. 17.864 − 99 =
  18. 18.25 + 19 =
  19. 19.44 − 9 =
  20. 20.21 + 19 =
  21. 21.52 + 29 =
  22. 22.73 + 19 =
  23. 23.80 + 9 =
  24. 24.253 + 99 =
  25. 25.653 + 99 =
  26. 26.813 − 99 =
  27. 27.548 − 99 =
  28. 28.48 + 9 =
  29. 29.35 − 29 =
  30. 30.94 − 19 =
  31. 31.39 + 19 =
  32. 32.631 + 99 =
  33. 33.709 + 99 =
  34. 34.35 − 19 =
  35. 35.48 + 19 =
  36. 36.108 + 99 =
  37. 37.108 − 29 =
  38. 38.67 + 29 =
  39. 39.296 + 99 =
  40. 40.370 − 99 =

Answer key

  1. 40
  2. 50
  3. 410
  4. 77
  5. 108
  6. 38
  7. 102
  8. 69
  9. 621
  10. 77
  11. 89
  12. 43
  13. 34
  14. 50
  15. 48
  16. 56
  17. 765
  18. 44
  19. 35
  20. 40
  21. 81
  22. 92
  23. 89
  24. 352
  25. 752
  26. 714
  27. 449
  28. 57
  29. 6
  30. 75
  31. 58
  32. 730
  33. 808
  34. 16
  35. 67
  36. 207
  37. 79
  38. 96
  39. 395
  40. 271

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