← 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 821 · 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. 1.772 − 99 =
  2. 2.501 + 99 =
  3. 3.323 + 99 =
  4. 4.22 + 19 =
  5. 5.483 + 99 =
  6. 6.52 − 29 =
  7. 7.103 − 29 =
  8. 8.32 − 29 =
  9. 9.34 − 9 =
  10. 10.86 − 9 =
  11. 11.38 + 9 =
  12. 12.20 + 29 =
  13. 13.69 + 19 =
  14. 14.13 − 9 =
  15. 15.515 − 99 =
  16. 16.21 − 9 =
  17. 17.55 + 9 =
  18. 18.87 − 19 =
  19. 19.28 − 9 =
  20. 20.731 + 99 =
  21. 21.551 + 99 =
  22. 22.46 + 9 =
  23. 23.23 + 9 =
  24. 24.15 − 9 =
  25. 25.69 + 9 =
  26. 26.65 − 9 =
  27. 27.34 − 19 =
  28. 28.281 − 99 =
  29. 29.67 − 19 =
  30. 30.783 + 99 =
  31. 31.431 − 99 =
  32. 32.314 + 99 =
  33. 33.54 − 9 =
  34. 34.106 − 29 =
  35. 35.80 − 29 =
  36. 36.71 + 19 =
  37. 37.270 + 99 =
  38. 38.79 + 29 =
  39. 39.24 + 29 =
  40. 40.205 − 99 =

Answer key

  1. 673
  2. 600
  3. 422
  4. 41
  5. 582
  6. 23
  7. 74
  8. 3
  9. 25
  10. 77
  11. 47
  12. 49
  13. 88
  14. 4
  15. 416
  16. 12
  17. 64
  18. 68
  19. 19
  20. 830
  21. 650
  22. 55
  23. 32
  24. 6
  25. 78
  26. 56
  27. 15
  28. 182
  29. 48
  30. 882
  31. 332
  32. 413
  33. 45
  34. 77
  35. 51
  36. 90
  37. 369
  38. 108
  39. 53
  40. 106

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