← 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 33 · 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. 1.749 + 99 =
  2. 2.65 − 9 =
  3. 3.605 + 99 =
  4. 4.29 − 19 =
  5. 5.323 − 99 =
  6. 6.872 − 99 =
  7. 7.27 + 19 =
  8. 8.230 + 99 =
  9. 9.72 − 19 =
  10. 10.390 − 99 =
  11. 11.54 − 9 =
  12. 12.45 − 19 =
  13. 13.54 + 9 =
  14. 14.35 − 19 =
  15. 15.761 + 99 =
  16. 16.30 + 19 =
  17. 17.34 + 19 =
  18. 18.35 − 9 =
  19. 19.708 − 99 =
  20. 20.740 + 99 =
  21. 21.95 − 29 =
  22. 22.548 − 99 =
  23. 23.212 + 99 =
  24. 24.753 + 99 =
  25. 25.200 + 99 =
  26. 26.37 + 19 =
  27. 27.21 + 9 =
  28. 28.562 − 99 =
  29. 29.107 − 29 =
  30. 30.36 + 19 =
  31. 31.48 + 9 =
  32. 32.31 − 19 =
  33. 33.175 + 99 =
  34. 34.75 − 9 =
  35. 35.18 + 29 =
  36. 36.53 − 9 =
  37. 37.48 − 29 =
  38. 38.70 + 29 =
  39. 39.92 − 29 =
  40. 40.60 + 29 =

Answer key

  1. 848
  2. 56
  3. 704
  4. 10
  5. 224
  6. 773
  7. 46
  8. 329
  9. 53
  10. 291
  11. 45
  12. 26
  13. 63
  14. 16
  15. 860
  16. 49
  17. 53
  18. 26
  19. 609
  20. 839
  21. 66
  22. 449
  23. 311
  24. 852
  25. 299
  26. 56
  27. 30
  28. 463
  29. 78
  30. 55
  31. 57
  32. 12
  33. 274
  34. 66
  35. 47
  36. 44
  37. 19
  38. 99
  39. 63
  40. 89

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