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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 725 · 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. 1.344 + 679 =
  2. 2.136 + 437 =
  3. 3.792 − 472 =
  4. 4.660 − 291 =
  5. 5.701 − 233 =
  6. 6.624 − 193 =
  7. 7.418 + 291 =
  8. 8.295 + 508 =
  9. 9.712 + 322 =
  10. 10.534 − 387 =
  11. 11.583 + 328 =
  12. 12.290 + 641 =
  13. 13.720 + 654 =
  14. 14.187 + 203 =
  15. 15.801 − 441 =
  16. 16.137 + 408 =
  17. 17.276 + 538 =
  18. 18.773 + 256 =
  19. 19.582 + 284 =
  20. 20.575 + 463 =
  21. 21.142 + 226 =
  22. 22.725 − 261 =
  23. 23.838 − 575 =
  24. 24.790 − 466 =
  25. 25.353 + 445 =
  26. 26.784 + 548 =
  27. 27.910 − 345 =
  28. 28.476 − 306 =
  29. 29.861 − 621 =
  30. 30.419 + 159 =
  31. 31.707 − 391 =
  32. 32.546 − 265 =
  33. 33.758 − 307 =
  34. 34.768 − 307 =
  35. 35.609 − 295 =
  36. 36.788 − 323 =
  37. 37.478 − 182 =
  38. 38.247 + 129 =
  39. 39.582 − 479 =
  40. 40.551 + 594 =

Answer key

  1. 1023
  2. 573
  3. 320
  4. 369
  5. 468
  6. 431
  7. 709
  8. 803
  9. 1034
  10. 147
  11. 911
  12. 931
  13. 1374
  14. 390
  15. 360
  16. 545
  17. 814
  18. 1029
  19. 866
  20. 1038
  21. 368
  22. 464
  23. 263
  24. 324
  25. 798
  26. 1332
  27. 565
  28. 170
  29. 240
  30. 578
  31. 316
  32. 281
  33. 451
  34. 461
  35. 314
  36. 465
  37. 296
  38. 376
  39. 103
  40. 1145

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