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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 871 · 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. 1.837 − 507 =
  2. 2.597 + 572 =
  3. 3.887 − 467 =
  4. 4.131 + 671 =
  5. 5.578 + 605 =
  6. 6.457 − 182 =
  7. 7.588 + 655 =
  8. 8.473 − 362 =
  9. 9.768 − 203 =
  10. 10.697 − 581 =
  11. 11.653 − 321 =
  12. 12.977 − 773 =
  13. 13.478 + 473 =
  14. 14.559 − 443 =
  15. 15.588 + 677 =
  16. 16.659 + 488 =
  17. 17.474 + 312 =
  18. 18.586 + 298 =
  19. 19.454 − 185 =
  20. 20.928 − 141 =
  21. 21.536 − 149 =
  22. 22.170 + 668 =
  23. 23.587 − 173 =
  24. 24.209 + 282 =
  25. 25.813 − 551 =
  26. 26.453 − 317 =
  27. 27.367 + 206 =
  28. 28.971 − 395 =
  29. 29.318 + 659 =
  30. 30.751 + 643 =
  31. 31.517 + 623 =
  32. 32.478 − 324 =
  33. 33.862 − 301 =
  34. 34.604 − 151 =
  35. 35.344 + 142 =
  36. 36.799 − 216 =
  37. 37.616 + 443 =
  38. 38.754 − 175 =
  39. 39.284 + 566 =
  40. 40.412 − 301 =

Answer key

  1. 330
  2. 1169
  3. 420
  4. 802
  5. 1183
  6. 275
  7. 1243
  8. 111
  9. 565
  10. 116
  11. 332
  12. 204
  13. 951
  14. 116
  15. 1265
  16. 1147
  17. 786
  18. 884
  19. 269
  20. 787
  21. 387
  22. 838
  23. 414
  24. 491
  25. 262
  26. 136
  27. 573
  28. 576
  29. 977
  30. 1394
  31. 1140
  32. 154
  33. 561
  34. 453
  35. 486
  36. 583
  37. 1059
  38. 579
  39. 850
  40. 111

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