← 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 400 · 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. 1.54 + 9 =
  2. 2.313 + 99 =
  3. 3.45 + 9 =
  4. 4.126 + 99 =
  5. 5.352 − 99 =
  6. 6.24 + 9 =
  7. 7.29 + 29 =
  8. 8.510 − 99 =
  9. 9.83 − 19 =
  10. 10.78 + 19 =
  11. 11.630 + 99 =
  12. 12.77 − 29 =
  13. 13.71 − 29 =
  14. 14.42 + 29 =
  15. 15.556 + 99 =
  16. 16.30 − 19 =
  17. 17.234 + 99 =
  18. 18.48 − 9 =
  19. 19.482 + 99 =
  20. 20.37 − 19 =
  21. 21.43 + 9 =
  22. 22.25 + 9 =
  23. 23.23 + 29 =
  24. 24.64 + 19 =
  25. 25.253 + 99 =
  26. 26.21 + 19 =
  27. 27.66 + 29 =
  28. 28.41 + 19 =
  29. 29.58 − 9 =
  30. 30.43 − 9 =
  31. 31.74 + 19 =
  32. 32.29 − 9 =
  33. 33.162 + 99 =
  34. 34.19 + 29 =
  35. 35.463 − 99 =
  36. 36.84 − 29 =
  37. 37.69 − 9 =
  38. 38.46 − 9 =
  39. 39.24 + 29 =
  40. 40.582 + 99 =

Answer key

  1. 63
  2. 412
  3. 54
  4. 225
  5. 253
  6. 33
  7. 58
  8. 411
  9. 64
  10. 97
  11. 729
  12. 48
  13. 42
  14. 71
  15. 655
  16. 11
  17. 333
  18. 39
  19. 581
  20. 18
  21. 52
  22. 34
  23. 52
  24. 83
  25. 352
  26. 40
  27. 95
  28. 60
  29. 49
  30. 34
  31. 93
  32. 20
  33. 261
  34. 48
  35. 364
  36. 55
  37. 60
  38. 37
  39. 53
  40. 681

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