← 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 209 · 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. 1.494 + 99 =
  2. 2.790 + 99 =
  3. 3.54 − 9 =
  4. 4.46 + 9 =
  5. 5.303 − 99 =
  6. 6.24 + 9 =
  7. 7.62 − 19 =
  8. 8.510 + 99 =
  9. 9.51 + 19 =
  10. 10.578 + 99 =
  11. 11.70 − 9 =
  12. 12.96 − 19 =
  13. 13.158 + 99 =
  14. 14.88 − 9 =
  15. 15.75 − 9 =
  16. 16.65 − 9 =
  17. 17.853 − 99 =
  18. 18.19 + 9 =
  19. 19.15 + 9 =
  20. 20.34 + 9 =
  21. 21.78 + 29 =
  22. 22.40 − 9 =
  23. 23.156 − 99 =
  24. 24.35 + 29 =
  25. 25.67 − 19 =
  26. 26.122 + 99 =
  27. 27.29 + 29 =
  28. 28.69 + 29 =
  29. 29.32 + 9 =
  30. 30.60 + 19 =
  31. 31.39 + 19 =
  32. 32.49 − 9 =
  33. 33.58 + 29 =
  34. 34.98 − 19 =
  35. 35.23 + 29 =
  36. 36.41 + 29 =
  37. 37.637 − 99 =
  38. 38.27 + 9 =
  39. 39.34 − 29 =
  40. 40.161 − 99 =

Answer key

  1. 593
  2. 889
  3. 45
  4. 55
  5. 204
  6. 33
  7. 43
  8. 609
  9. 70
  10. 677
  11. 61
  12. 77
  13. 257
  14. 79
  15. 66
  16. 56
  17. 754
  18. 28
  19. 24
  20. 43
  21. 107
  22. 31
  23. 57
  24. 64
  25. 48
  26. 221
  27. 58
  28. 98
  29. 41
  30. 79
  31. 58
  32. 40
  33. 87
  34. 79
  35. 52
  36. 70
  37. 538
  38. 36
  39. 5
  40. 62

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