← 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 724 · 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. 1.38 + 9 =
  2. 2.782 − 99 =
  3. 3.262 + 99 =
  4. 4.61 − 9 =
  5. 5.105 − 29 =
  6. 6.379 − 99 =
  7. 7.269 − 99 =
  8. 8.18 + 9 =
  9. 9.532 − 99 =
  10. 10.54 + 9 =
  11. 11.16 + 9 =
  12. 12.620 + 99 =
  13. 13.63 − 29 =
  14. 14.22 + 29 =
  15. 15.40 + 9 =
  16. 16.65 + 29 =
  17. 17.557 − 99 =
  18. 18.44 − 29 =
  19. 19.28 − 19 =
  20. 20.72 − 9 =
  21. 21.22 − 19 =
  22. 22.71 − 29 =
  23. 23.34 − 9 =
  24. 24.50 + 9 =
  25. 25.80 + 9 =
  26. 26.23 + 19 =
  27. 27.583 − 99 =
  28. 28.31 + 29 =
  29. 29.47 − 9 =
  30. 30.29 + 9 =
  31. 31.538 + 99 =
  32. 32.268 − 99 =
  33. 33.36 − 19 =
  34. 34.15 + 19 =
  35. 35.234 − 99 =
  36. 36.50 − 19 =
  37. 37.761 + 99 =
  38. 38.60 − 9 =
  39. 39.77 + 19 =
  40. 40.38 + 29 =

Answer key

  1. 47
  2. 683
  3. 361
  4. 52
  5. 76
  6. 280
  7. 170
  8. 27
  9. 433
  10. 63
  11. 25
  12. 719
  13. 34
  14. 51
  15. 49
  16. 94
  17. 458
  18. 15
  19. 9
  20. 63
  21. 3
  22. 42
  23. 25
  24. 59
  25. 89
  26. 42
  27. 484
  28. 60
  29. 38
  30. 38
  31. 637
  32. 169
  33. 17
  34. 34
  35. 135
  36. 31
  37. 860
  38. 51
  39. 96
  40. 67

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