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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 63 · 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. 1.633 + 648 =
  2. 2.453 + 588 =
  3. 3.451 − 286 =
  4. 4.739 − 337 =
  5. 5.378 + 557 =
  6. 6.582 − 231 =
  7. 7.246 + 253 =
  8. 8.420 + 187 =
  9. 9.763 − 139 =
  10. 10.406 + 584 =
  11. 11.192 + 286 =
  12. 12.640 + 515 =
  13. 13.552 + 329 =
  14. 14.160 + 441 =
  15. 15.148 + 296 =
  16. 16.657 − 525 =
  17. 17.711 + 651 =
  18. 18.845 − 177 =
  19. 19.527 + 251 =
  20. 20.734 − 211 =
  21. 21.701 + 389 =
  22. 22.780 + 304 =
  23. 23.660 + 191 =
  24. 24.207 + 669 =
  25. 25.594 + 671 =
  26. 26.709 − 114 =
  27. 27.628 − 121 =
  28. 28.544 + 134 =
  29. 29.698 − 199 =
  30. 30.695 + 226 =
  31. 31.307 + 139 =
  32. 32.738 + 314 =
  33. 33.859 − 421 =
  34. 34.219 + 181 =
  35. 35.513 + 411 =
  36. 36.206 + 251 =
  37. 37.552 + 123 =
  38. 38.773 − 163 =
  39. 39.775 − 146 =
  40. 40.734 − 198 =

Answer key

  1. 1281
  2. 1041
  3. 165
  4. 402
  5. 935
  6. 351
  7. 499
  8. 607
  9. 624
  10. 990
  11. 478
  12. 1155
  13. 881
  14. 601
  15. 444
  16. 132
  17. 1362
  18. 668
  19. 778
  20. 523
  21. 1090
  22. 1084
  23. 851
  24. 876
  25. 1265
  26. 595
  27. 507
  28. 678
  29. 499
  30. 921
  31. 446
  32. 1052
  33. 438
  34. 400
  35. 924
  36. 457
  37. 675
  38. 610
  39. 629
  40. 536

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