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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 916 · 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. 1.213 + 266 =
  2. 2.664 − 304 =
  3. 3.495 − 114 =
  4. 4.973 − 787 =
  5. 5.761 − 361 =
  6. 6.555 − 411 =
  7. 7.445 + 178 =
  8. 8.492 + 257 =
  9. 9.416 − 253 =
  10. 10.702 + 462 =
  11. 11.599 − 491 =
  12. 12.484 + 184 =
  13. 13.909 − 455 =
  14. 14.460 + 197 =
  15. 15.414 + 307 =
  16. 16.388 + 221 =
  17. 17.316 + 126 =
  18. 18.965 − 631 =
  19. 19.718 − 298 =
  20. 20.815 − 199 =
  21. 21.709 + 201 =
  22. 22.383 + 525 =
  23. 23.184 + 365 =
  24. 24.167 + 563 =
  25. 25.687 − 339 =
  26. 26.902 − 557 =
  27. 27.548 + 656 =
  28. 28.980 − 708 =
  29. 29.883 − 398 =
  30. 30.210 + 265 =
  31. 31.435 + 539 =
  32. 32.551 − 146 =
  33. 33.399 + 607 =
  34. 34.983 − 175 =
  35. 35.524 − 245 =
  36. 36.717 + 394 =
  37. 37.500 + 221 =
  38. 38.689 − 477 =
  39. 39.685 + 446 =
  40. 40.449 − 208 =

Answer key

  1. 479
  2. 360
  3. 381
  4. 186
  5. 400
  6. 144
  7. 623
  8. 749
  9. 163
  10. 1164
  11. 108
  12. 668
  13. 454
  14. 657
  15. 721
  16. 609
  17. 442
  18. 334
  19. 420
  20. 616
  21. 910
  22. 908
  23. 549
  24. 730
  25. 348
  26. 345
  27. 1204
  28. 272
  29. 485
  30. 475
  31. 974
  32. 405
  33. 1006
  34. 808
  35. 279
  36. 1111
  37. 721
  38. 212
  39. 1131
  40. 241

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