← 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 74 · 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. 1.987 − 485 =
  2. 2.308 + 138 =
  3. 3.229 + 292 =
  4. 4.445 − 222 =
  5. 5.782 − 137 =
  6. 6.482 + 487 =
  7. 7.147 + 486 =
  8. 8.573 + 388 =
  9. 9.150 + 429 =
  10. 10.490 + 238 =
  11. 11.222 + 307 =
  12. 12.752 − 457 =
  13. 13.611 + 671 =
  14. 14.913 − 583 =
  15. 15.150 + 656 =
  16. 16.203 + 502 =
  17. 17.645 + 327 =
  18. 18.489 − 207 =
  19. 19.468 + 415 =
  20. 20.913 − 613 =
  21. 21.531 − 247 =
  22. 22.470 − 293 =
  23. 23.423 + 632 =
  24. 24.180 + 586 =
  25. 25.443 − 305 =
  26. 26.376 + 484 =
  27. 27.736 + 163 =
  28. 28.474 − 231 =
  29. 29.686 − 441 =
  30. 30.177 + 401 =
  31. 31.147 + 306 =
  32. 32.410 + 281 =
  33. 33.202 + 533 =
  34. 34.689 + 126 =
  35. 35.392 + 244 =
  36. 36.460 − 147 =
  37. 37.506 − 161 =
  38. 38.947 − 714 =
  39. 39.862 − 692 =
  40. 40.815 − 261 =

Answer key

  1. 502
  2. 446
  3. 521
  4. 223
  5. 645
  6. 969
  7. 633
  8. 961
  9. 579
  10. 728
  11. 529
  12. 295
  13. 1282
  14. 330
  15. 806
  16. 705
  17. 972
  18. 282
  19. 883
  20. 300
  21. 284
  22. 177
  23. 1055
  24. 766
  25. 138
  26. 860
  27. 899
  28. 243
  29. 245
  30. 578
  31. 453
  32. 691
  33. 735
  34. 815
  35. 636
  36. 313
  37. 345
  38. 233
  39. 170
  40. 554

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