← 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 121 · 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. 1.750 + 99 =
  2. 2.656 − 99 =
  3. 3.64 + 9 =
  4. 4.70 + 9 =
  5. 5.59 + 29 =
  6. 6.63 + 19 =
  7. 7.50 + 9 =
  8. 8.67 − 29 =
  9. 9.67 + 9 =
  10. 10.670 + 99 =
  11. 11.66 − 19 =
  12. 12.54 − 29 =
  13. 13.684 + 99 =
  14. 14.760 − 99 =
  15. 15.63 − 29 =
  16. 16.27 + 19 =
  17. 17.41 + 9 =
  18. 18.19 + 19 =
  19. 19.54 + 29 =
  20. 20.65 − 29 =
  21. 21.53 − 29 =
  22. 22.541 − 99 =
  23. 23.83 − 9 =
  24. 24.67 + 19 =
  25. 25.737 − 99 =
  26. 26.23 + 29 =
  27. 27.28 − 19 =
  28. 28.282 − 99 =
  29. 29.25 − 19 =
  30. 30.58 − 29 =
  31. 31.77 + 9 =
  32. 32.39 − 29 =
  33. 33.59 + 9 =
  34. 34.58 + 19 =
  35. 35.24 + 29 =
  36. 36.35 + 29 =
  37. 37.84 − 29 =
  38. 38.82 − 19 =
  39. 39.53 − 19 =
  40. 40.37 + 19 =

Answer key

  1. 849
  2. 557
  3. 73
  4. 79
  5. 88
  6. 82
  7. 59
  8. 38
  9. 76
  10. 769
  11. 47
  12. 25
  13. 783
  14. 661
  15. 34
  16. 46
  17. 50
  18. 38
  19. 83
  20. 36
  21. 24
  22. 442
  23. 74
  24. 86
  25. 638
  26. 52
  27. 9
  28. 183
  29. 6
  30. 29
  31. 86
  32. 10
  33. 68
  34. 77
  35. 53
  36. 64
  37. 55
  38. 63
  39. 34
  40. 56

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