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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 363 · 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. 1.335 + 212 =
  2. 2.516 − 238 =
  3. 3.580 − 124 =
  4. 4.357 + 117 =
  5. 5.499 + 157 =
  6. 6.661 − 372 =
  7. 7.753 − 162 =
  8. 8.784 − 515 =
  9. 9.348 + 419 =
  10. 10.759 + 483 =
  11. 11.416 + 627 =
  12. 12.166 + 191 =
  13. 13.568 + 395 =
  14. 14.427 + 191 =
  15. 15.767 + 647 =
  16. 16.742 − 284 =
  17. 17.284 + 371 =
  18. 18.860 − 549 =
  19. 19.314 + 272 =
  20. 20.978 − 707 =
  21. 21.312 + 644 =
  22. 22.960 − 856 =
  23. 23.180 + 148 =
  24. 24.744 − 642 =
  25. 25.633 + 149 =
  26. 26.448 − 338 =
  27. 27.410 + 541 =
  28. 28.610 + 651 =
  29. 29.202 + 383 =
  30. 30.532 + 395 =
  31. 31.539 + 291 =
  32. 32.416 − 287 =
  33. 33.374 + 159 =
  34. 34.630 + 242 =
  35. 35.460 − 235 =
  36. 36.791 − 533 =
  37. 37.706 + 221 =
  38. 38.623 + 261 =
  39. 39.187 + 366 =
  40. 40.698 + 283 =

Answer key

  1. 547
  2. 278
  3. 456
  4. 474
  5. 656
  6. 289
  7. 591
  8. 269
  9. 767
  10. 1242
  11. 1043
  12. 357
  13. 963
  14. 618
  15. 1414
  16. 458
  17. 655
  18. 311
  19. 586
  20. 271
  21. 956
  22. 104
  23. 328
  24. 102
  25. 782
  26. 110
  27. 951
  28. 1261
  29. 585
  30. 927
  31. 830
  32. 129
  33. 533
  34. 872
  35. 225
  36. 258
  37. 927
  38. 884
  39. 553
  40. 981

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