← 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 129 · 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. 1.108 − 29 =
  2. 2.124 + 99 =
  3. 3.63 + 9 =
  4. 4.56 + 29 =
  5. 5.622 + 99 =
  6. 6.14 − 9 =
  7. 7.59 + 9 =
  8. 8.34 + 19 =
  9. 9.13 + 29 =
  10. 10.79 + 29 =
  11. 11.32 + 19 =
  12. 12.85 − 9 =
  13. 13.31 + 9 =
  14. 14.76 + 9 =
  15. 15.38 + 29 =
  16. 16.665 − 99 =
  17. 17.161 + 99 =
  18. 18.84 − 9 =
  19. 19.67 − 9 =
  20. 20.711 + 99 =
  21. 21.27 + 29 =
  22. 22.803 − 99 =
  23. 23.307 + 99 =
  24. 24.41 − 19 =
  25. 25.261 − 99 =
  26. 26.13 − 9 =
  27. 27.27 − 9 =
  28. 28.41 − 29 =
  29. 29.22 + 29 =
  30. 30.621 − 99 =
  31. 31.49 + 9 =
  32. 32.714 − 99 =
  33. 33.18 + 19 =
  34. 34.102 − 29 =
  35. 35.571 + 99 =
  36. 36.21 + 19 =
  37. 37.687 − 99 =
  38. 38.23 + 29 =
  39. 39.256 + 99 =
  40. 40.51 + 29 =

Answer key

  1. 79
  2. 223
  3. 72
  4. 85
  5. 721
  6. 5
  7. 68
  8. 53
  9. 42
  10. 108
  11. 51
  12. 76
  13. 40
  14. 85
  15. 67
  16. 566
  17. 260
  18. 75
  19. 58
  20. 810
  21. 56
  22. 704
  23. 406
  24. 22
  25. 162
  26. 4
  27. 18
  28. 12
  29. 51
  30. 522
  31. 58
  32. 615
  33. 37
  34. 73
  35. 670
  36. 40
  37. 588
  38. 52
  39. 355
  40. 80

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