← Add and subtract 3-digit numbers left to right lesson New set →

3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 412 · 40 questions
TalentJR

How to do it in your head (Hundreds first): Keep the first number as it is and split the second into hundreds, tens and ones. Add (or take away) the hundreds first, then the tens. Finish with the ones — bridge through a ten if you need to.

NameDateTime takenScore ___ / 40
  1. 1.874 − 735 =
  2. 2.813 − 389 =
  3. 3.464 − 239 =
  4. 4.502 + 491 =
  5. 5.713 + 457 =
  6. 6.917 − 733 =
  7. 7.404 + 458 =
  8. 8.610 + 414 =
  9. 9.918 − 297 =
  10. 10.257 + 409 =
  11. 11.205 + 637 =
  12. 12.732 + 638 =
  13. 13.712 + 677 =
  14. 14.180 + 641 =
  15. 15.843 − 211 =
  16. 16.808 − 329 =
  17. 17.963 − 186 =
  18. 18.866 − 205 =
  19. 19.680 + 394 =
  20. 20.128 + 143 =
  21. 21.605 − 195 =
  22. 22.443 − 317 =
  23. 23.477 − 161 =
  24. 24.533 − 168 =
  25. 25.893 − 432 =
  26. 26.252 + 198 =
  27. 27.974 − 681 =
  28. 28.310 + 606 =
  29. 29.315 + 409 =
  30. 30.153 + 476 =
  31. 31.319 + 609 =
  32. 32.493 + 278 =
  33. 33.628 − 244 =
  34. 34.731 − 571 =
  35. 35.850 − 211 =
  36. 36.682 + 241 =
  37. 37.558 − 203 =
  38. 38.523 + 431 =
  39. 39.484 − 114 =
  40. 40.567 − 341 =

Answer key

  1. 139
  2. 424
  3. 225
  4. 993
  5. 1170
  6. 184
  7. 862
  8. 1024
  9. 621
  10. 666
  11. 842
  12. 1370
  13. 1389
  14. 821
  15. 632
  16. 479
  17. 777
  18. 661
  19. 1074
  20. 271
  21. 410
  22. 126
  23. 316
  24. 365
  25. 461
  26. 450
  27. 293
  28. 916
  29. 724
  30. 629
  31. 928
  32. 771
  33. 384
  34. 160
  35. 639
  36. 923
  37. 355
  38. 954
  39. 370
  40. 226

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