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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 501 · 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. 1.569 − 308 =
  2. 2.740 − 279 =
  3. 3.948 − 652 =
  4. 4.695 − 165 =
  5. 5.540 − 427 =
  6. 6.524 − 144 =
  7. 7.746 − 206 =
  8. 8.261 + 411 =
  9. 9.437 − 245 =
  10. 10.165 + 179 =
  11. 11.697 + 139 =
  12. 12.232 + 559 =
  13. 13.528 − 166 =
  14. 14.946 − 349 =
  15. 15.421 + 146 =
  16. 16.468 − 198 =
  17. 17.441 + 223 =
  18. 18.139 + 387 =
  19. 19.577 − 401 =
  20. 20.816 − 601 =
  21. 21.760 + 637 =
  22. 22.729 + 603 =
  23. 23.318 + 494 =
  24. 24.658 − 319 =
  25. 25.858 − 341 =
  26. 26.476 + 283 =
  27. 27.765 − 366 =
  28. 28.816 − 192 =
  29. 29.724 − 139 =
  30. 30.236 + 295 =
  31. 31.228 + 317 =
  32. 32.328 + 501 =
  33. 33.190 + 555 =
  34. 34.716 + 363 =
  35. 35.431 + 582 =
  36. 36.744 + 641 =
  37. 37.622 + 668 =
  38. 38.726 + 281 =
  39. 39.278 + 582 =
  40. 40.521 + 152 =

Answer key

  1. 261
  2. 461
  3. 296
  4. 530
  5. 113
  6. 380
  7. 540
  8. 672
  9. 192
  10. 344
  11. 836
  12. 791
  13. 362
  14. 597
  15. 567
  16. 270
  17. 664
  18. 526
  19. 176
  20. 215
  21. 1397
  22. 1332
  23. 812
  24. 339
  25. 517
  26. 759
  27. 399
  28. 624
  29. 585
  30. 531
  31. 545
  32. 829
  33. 745
  34. 1079
  35. 1013
  36. 1385
  37. 1290
  38. 1007
  39. 860
  40. 673

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