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3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 236 · 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. 1.736 + 547 =
  2. 2.941 − 183 =
  3. 3.715 − 322 =
  4. 4.775 + 653 =
  5. 5.506 + 244 =
  6. 6.753 − 175 =
  7. 7.376 + 641 =
  8. 8.579 − 401 =
  9. 9.700 + 613 =
  10. 10.212 + 296 =
  11. 11.723 + 422 =
  12. 12.482 − 167 =
  13. 13.709 − 498 =
  14. 14.830 − 431 =
  15. 15.476 + 551 =
  16. 16.575 − 215 =
  17. 17.349 + 643 =
  18. 18.548 + 683 =
  19. 19.653 − 382 =
  20. 20.483 + 301 =
  21. 21.862 − 291 =
  22. 22.362 + 411 =
  23. 23.702 + 207 =
  24. 24.724 + 544 =
  25. 25.387 + 441 =
  26. 26.730 + 527 =
  27. 27.563 − 369 =
  28. 28.634 + 678 =
  29. 29.359 + 615 =
  30. 30.857 − 622 =
  31. 31.545 + 314 =
  32. 32.544 − 332 =
  33. 33.371 + 687 =
  34. 34.576 − 124 =
  35. 35.606 − 348 =
  36. 36.681 − 423 =
  37. 37.587 + 627 =
  38. 38.645 − 521 =
  39. 39.573 − 431 =
  40. 40.540 − 408 =

Answer key

  1. 1283
  2. 758
  3. 393
  4. 1428
  5. 750
  6. 578
  7. 1017
  8. 178
  9. 1313
  10. 508
  11. 1145
  12. 315
  13. 211
  14. 399
  15. 1027
  16. 360
  17. 992
  18. 1231
  19. 271
  20. 784
  21. 571
  22. 773
  23. 909
  24. 1268
  25. 828
  26. 1257
  27. 194
  28. 1312
  29. 974
  30. 235
  31. 859
  32. 212
  33. 1058
  34. 452
  35. 258
  36. 258
  37. 1214
  38. 124
  39. 142
  40. 132

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