← 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 687 · 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. 1.770 − 99 =
  2. 2.26 + 9 =
  3. 3.75 + 29 =
  4. 4.77 + 9 =
  5. 5.495 + 99 =
  6. 6.33 + 29 =
  7. 7.58 + 29 =
  8. 8.30 + 29 =
  9. 9.28 + 9 =
  10. 10.796 − 99 =
  11. 11.66 + 19 =
  12. 12.21 − 9 =
  13. 13.25 + 9 =
  14. 14.33 + 19 =
  15. 15.32 − 19 =
  16. 16.71 + 19 =
  17. 17.77 − 29 =
  18. 18.55 + 29 =
  19. 19.207 − 99 =
  20. 20.252 + 99 =
  21. 21.47 + 9 =
  22. 22.12 − 9 =
  23. 23.88 − 9 =
  24. 24.99 − 19 =
  25. 25.80 + 19 =
  26. 26.235 − 99 =
  27. 27.80 + 29 =
  28. 28.64 − 19 =
  29. 29.69 + 9 =
  30. 30.100 − 29 =
  31. 31.29 + 9 =
  32. 32.22 + 9 =
  33. 33.61 − 29 =
  34. 34.59 + 9 =
  35. 35.51 + 19 =
  36. 36.67 − 19 =
  37. 37.37 − 29 =
  38. 38.303 − 99 =
  39. 39.68 − 19 =
  40. 40.30 − 9 =

Answer key

  1. 671
  2. 35
  3. 104
  4. 86
  5. 594
  6. 62
  7. 87
  8. 59
  9. 37
  10. 697
  11. 85
  12. 12
  13. 34
  14. 52
  15. 13
  16. 90
  17. 48
  18. 84
  19. 108
  20. 351
  21. 56
  22. 3
  23. 79
  24. 80
  25. 99
  26. 136
  27. 109
  28. 45
  29. 78
  30. 71
  31. 38
  32. 31
  33. 32
  34. 68
  35. 70
  36. 48
  37. 8
  38. 204
  39. 49
  40. 21

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