← 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 739 · 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. 1.23 − 9 =
  2. 2.580 + 99 =
  3. 3.36 − 29 =
  4. 4.742 + 99 =
  5. 5.61 + 19 =
  6. 6.68 − 29 =
  7. 7.40 + 9 =
  8. 8.82 − 29 =
  9. 9.62 − 9 =
  10. 10.509 − 99 =
  11. 11.62 + 19 =
  12. 12.92 − 29 =
  13. 13.26 − 9 =
  14. 14.52 − 29 =
  15. 15.184 + 99 =
  16. 16.859 − 99 =
  17. 17.266 + 99 =
  18. 18.55 − 9 =
  19. 19.73 − 29 =
  20. 20.97 − 19 =
  21. 21.759 + 99 =
  22. 22.16 − 9 =
  23. 23.35 + 19 =
  24. 24.32 − 19 =
  25. 25.40 + 29 =
  26. 26.53 − 29 =
  27. 27.22 + 9 =
  28. 28.89 − 9 =
  29. 29.174 + 99 =
  30. 30.81 − 29 =
  31. 31.35 + 9 =
  32. 32.102 − 29 =
  33. 33.515 + 99 =
  34. 34.52 − 19 =
  35. 35.311 − 99 =
  36. 36.70 − 19 =
  37. 37.541 + 99 =
  38. 38.56 − 19 =
  39. 39.488 + 99 =
  40. 40.68 + 29 =

Answer key

  1. 14
  2. 679
  3. 7
  4. 841
  5. 80
  6. 39
  7. 49
  8. 53
  9. 53
  10. 410
  11. 81
  12. 63
  13. 17
  14. 23
  15. 283
  16. 760
  17. 365
  18. 46
  19. 44
  20. 78
  21. 858
  22. 7
  23. 54
  24. 13
  25. 69
  26. 24
  27. 31
  28. 80
  29. 273
  30. 52
  31. 44
  32. 73
  33. 614
  34. 33
  35. 212
  36. 51
  37. 640
  38. 37
  39. 587
  40. 97

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