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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 84 · 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. 1.954 − 761 =
  2. 2.567 − 226 =
  3. 3.442 − 342 =
  4. 4.491 + 543 =
  5. 5.470 − 138 =
  6. 6.699 − 321 =
  7. 7.634 + 648 =
  8. 8.159 + 403 =
  9. 9.743 + 242 =
  10. 10.734 − 238 =
  11. 11.686 − 374 =
  12. 12.142 + 471 =
  13. 13.161 + 557 =
  14. 14.657 − 403 =
  15. 15.298 + 463 =
  16. 16.890 − 646 =
  17. 17.729 + 191 =
  18. 18.641 − 502 =
  19. 19.832 − 714 =
  20. 20.933 − 397 =
  21. 21.408 + 182 =
  22. 22.458 − 237 =
  23. 23.291 + 431 =
  24. 24.560 + 571 =
  25. 25.717 − 366 =
  26. 26.350 + 338 =
  27. 27.426 + 675 =
  28. 28.296 + 172 =
  29. 29.201 + 418 =
  30. 30.654 − 351 =
  31. 31.200 + 679 =
  32. 32.435 − 266 =
  33. 33.726 − 472 =
  34. 34.509 + 658 =
  35. 35.138 + 511 =
  36. 36.176 + 254 =
  37. 37.845 − 622 =
  38. 38.344 + 213 =
  39. 39.593 + 488 =
  40. 40.295 + 363 =

Answer key

  1. 193
  2. 341
  3. 100
  4. 1034
  5. 332
  6. 378
  7. 1282
  8. 562
  9. 985
  10. 496
  11. 312
  12. 613
  13. 718
  14. 254
  15. 761
  16. 244
  17. 920
  18. 139
  19. 118
  20. 536
  21. 590
  22. 221
  23. 722
  24. 1131
  25. 351
  26. 688
  27. 1101
  28. 468
  29. 619
  30. 303
  31. 879
  32. 169
  33. 254
  34. 1167
  35. 649
  36. 430
  37. 223
  38. 557
  39. 1081
  40. 658

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