← 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 304 · 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. 1.636 − 186 =
  2. 2.192 + 281 =
  3. 3.582 + 397 =
  4. 4.282 + 138 =
  5. 5.869 − 252 =
  6. 6.748 − 191 =
  7. 7.505 + 202 =
  8. 8.616 + 677 =
  9. 9.628 + 411 =
  10. 10.824 − 564 =
  11. 11.626 − 496 =
  12. 12.430 − 317 =
  13. 13.493 − 193 =
  14. 14.768 − 267 =
  15. 15.317 + 572 =
  16. 16.933 − 235 =
  17. 17.464 + 537 =
  18. 18.815 − 244 =
  19. 19.776 − 508 =
  20. 20.777 − 368 =
  21. 21.620 + 614 =
  22. 22.607 + 223 =
  23. 23.650 + 466 =
  24. 24.352 + 397 =
  25. 25.568 + 329 =
  26. 26.654 + 299 =
  27. 27.260 + 507 =
  28. 28.418 − 143 =
  29. 29.726 − 277 =
  30. 30.507 − 341 =
  31. 31.918 − 258 =
  32. 32.301 + 201 =
  33. 33.773 − 479 =
  34. 34.878 − 648 =
  35. 35.485 + 471 =
  36. 36.755 + 688 =
  37. 37.758 + 379 =
  38. 38.624 − 135 =
  39. 39.621 + 214 =
  40. 40.465 − 295 =

Answer key

  1. 450
  2. 473
  3. 979
  4. 420
  5. 617
  6. 557
  7. 707
  8. 1293
  9. 1039
  10. 260
  11. 130
  12. 113
  13. 300
  14. 501
  15. 889
  16. 698
  17. 1001
  18. 571
  19. 268
  20. 409
  21. 1234
  22. 830
  23. 1116
  24. 749
  25. 897
  26. 953
  27. 767
  28. 275
  29. 449
  30. 166
  31. 660
  32. 502
  33. 294
  34. 230
  35. 956
  36. 1443
  37. 1137
  38. 489
  39. 835
  40. 170

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