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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 76 · 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. 1.662 − 174 =
  2. 2.517 + 118 =
  3. 3.960 − 765 =
  4. 4.558 + 422 =
  5. 5.777 − 187 =
  6. 6.601 + 555 =
  7. 7.166 + 366 =
  8. 8.762 + 519 =
  9. 9.441 − 113 =
  10. 10.833 − 481 =
  11. 11.839 − 199 =
  12. 12.678 − 202 =
  13. 13.471 + 136 =
  14. 14.541 + 343 =
  15. 15.533 − 189 =
  16. 16.536 − 283 =
  17. 17.185 + 642 =
  18. 18.770 + 561 =
  19. 19.769 + 161 =
  20. 20.396 + 326 =
  21. 21.570 + 323 =
  22. 22.316 + 629 =
  23. 23.615 − 482 =
  24. 24.913 − 544 =
  25. 25.212 + 137 =
  26. 26.282 + 401 =
  27. 27.417 − 169 =
  28. 28.142 + 391 =
  29. 29.880 − 281 =
  30. 30.968 − 342 =
  31. 31.204 + 246 =
  32. 32.454 + 262 =
  33. 33.683 + 532 =
  34. 34.431 + 119 =
  35. 35.229 + 236 =
  36. 36.191 + 267 =
  37. 37.518 + 398 =
  38. 38.367 + 217 =
  39. 39.779 − 562 =
  40. 40.198 + 337 =

Answer key

  1. 488
  2. 635
  3. 195
  4. 980
  5. 590
  6. 1156
  7. 532
  8. 1281
  9. 328
  10. 352
  11. 640
  12. 476
  13. 607
  14. 884
  15. 344
  16. 253
  17. 827
  18. 1331
  19. 930
  20. 722
  21. 893
  22. 945
  23. 133
  24. 369
  25. 349
  26. 683
  27. 248
  28. 533
  29. 599
  30. 626
  31. 450
  32. 716
  33. 1215
  34. 550
  35. 465
  36. 458
  37. 916
  38. 584
  39. 217
  40. 535

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