← 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 66 · 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. 1.308 − 99 =
  2. 2.822 − 99 =
  3. 3.83 − 29 =
  4. 4.761 − 99 =
  5. 5.55 − 9 =
  6. 6.24 + 29 =
  7. 7.429 + 99 =
  8. 8.77 + 9 =
  9. 9.67 + 19 =
  10. 10.64 + 9 =
  11. 11.14 + 19 =
  12. 12.104 − 29 =
  13. 13.290 + 99 =
  14. 14.80 − 29 =
  15. 15.55 + 9 =
  16. 16.339 + 99 =
  17. 17.378 + 99 =
  18. 18.41 + 9 =
  19. 19.150 − 99 =
  20. 20.30 + 29 =
  21. 21.12 + 29 =
  22. 22.166 − 99 =
  23. 23.31 − 19 =
  24. 24.574 − 99 =
  25. 25.81 − 19 =
  26. 26.486 + 99 =
  27. 27.21 + 19 =
  28. 28.178 + 99 =
  29. 29.581 − 99 =
  30. 30.62 + 29 =
  31. 31.37 + 9 =
  32. 32.72 + 9 =
  33. 33.353 + 99 =
  34. 34.488 + 99 =
  35. 35.87 − 29 =
  36. 36.166 + 99 =
  37. 37.66 + 29 =
  38. 38.24 + 9 =
  39. 39.62 − 9 =
  40. 40.55 + 29 =

Answer key

  1. 209
  2. 723
  3. 54
  4. 662
  5. 46
  6. 53
  7. 528
  8. 86
  9. 86
  10. 73
  11. 33
  12. 75
  13. 389
  14. 51
  15. 64
  16. 438
  17. 477
  18. 50
  19. 51
  20. 59
  21. 41
  22. 67
  23. 12
  24. 475
  25. 62
  26. 585
  27. 40
  28. 277
  29. 482
  30. 91
  31. 46
  32. 81
  33. 452
  34. 587
  35. 58
  36. 265
  37. 95
  38. 33
  39. 53
  40. 84

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