← 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 120 · 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. 1.75 + 29 =
  2. 2.26 + 9 =
  3. 3.84 − 9 =
  4. 4.593 + 99 =
  5. 5.29 + 9 =
  6. 6.223 + 99 =
  7. 7.50 + 9 =
  8. 8.79 + 29 =
  9. 9.39 − 9 =
  10. 10.61 − 29 =
  11. 11.30 + 9 =
  12. 12.79 + 19 =
  13. 13.156 + 99 =
  14. 14.52 + 9 =
  15. 15.65 + 19 =
  16. 16.59 − 9 =
  17. 17.46 − 9 =
  18. 18.382 − 99 =
  19. 19.65 − 29 =
  20. 20.57 + 19 =
  21. 21.89 − 9 =
  22. 22.35 + 9 =
  23. 23.78 + 29 =
  24. 24.301 − 99 =
  25. 25.45 + 19 =
  26. 26.63 + 29 =
  27. 27.537 + 99 =
  28. 28.29 + 19 =
  29. 29.801 − 99 =
  30. 30.709 − 99 =
  31. 31.81 − 9 =
  32. 32.838 − 99 =
  33. 33.64 + 19 =
  34. 34.58 + 9 =
  35. 35.53 + 19 =
  36. 36.44 − 9 =
  37. 37.605 + 99 =
  38. 38.13 + 19 =
  39. 39.91 − 29 =
  40. 40.61 + 9 =

Answer key

  1. 104
  2. 35
  3. 75
  4. 692
  5. 38
  6. 322
  7. 59
  8. 108
  9. 30
  10. 32
  11. 39
  12. 98
  13. 255
  14. 61
  15. 84
  16. 50
  17. 37
  18. 283
  19. 36
  20. 76
  21. 80
  22. 44
  23. 107
  24. 202
  25. 64
  26. 92
  27. 636
  28. 48
  29. 702
  30. 610
  31. 72
  32. 739
  33. 83
  34. 67
  35. 72
  36. 35
  37. 704
  38. 32
  39. 62
  40. 70

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