← 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 178 · 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. 1.239 − 99 =
  2. 2.45 − 29 =
  3. 3.43 + 9 =
  4. 4.96 − 19 =
  5. 5.46 − 29 =
  6. 6.873 − 99 =
  7. 7.42 − 29 =
  8. 8.98 − 29 =
  9. 9.46 + 9 =
  10. 10.189 − 99 =
  11. 11.99 − 19 =
  12. 12.44 + 29 =
  13. 13.877 − 99 =
  14. 14.72 + 9 =
  15. 15.76 − 29 =
  16. 16.68 − 19 =
  17. 17.14 + 29 =
  18. 18.550 + 99 =
  19. 19.41 − 9 =
  20. 20.39 − 29 =
  21. 21.64 − 9 =
  22. 22.719 + 99 =
  23. 23.70 + 29 =
  24. 24.47 − 9 =
  25. 25.42 − 9 =
  26. 26.272 + 99 =
  27. 27.41 + 19 =
  28. 28.62 − 9 =
  29. 29.84 − 19 =
  30. 30.677 + 99 =
  31. 31.38 − 9 =
  32. 32.217 + 99 =
  33. 33.30 + 9 =
  34. 34.53 + 29 =
  35. 35.145 + 99 =
  36. 36.25 + 19 =
  37. 37.104 − 29 =
  38. 38.19 + 9 =
  39. 39.55 − 9 =
  40. 40.687 + 99 =

Answer key

  1. 140
  2. 16
  3. 52
  4. 77
  5. 17
  6. 774
  7. 13
  8. 69
  9. 55
  10. 90
  11. 80
  12. 73
  13. 778
  14. 81
  15. 47
  16. 49
  17. 43
  18. 649
  19. 32
  20. 10
  21. 55
  22. 818
  23. 99
  24. 38
  25. 33
  26. 371
  27. 60
  28. 53
  29. 65
  30. 776
  31. 29
  32. 316
  33. 39
  34. 82
  35. 244
  36. 44
  37. 75
  38. 28
  39. 46
  40. 786

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