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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 550 · 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. 1.171 + 227 =
  2. 2.484 − 265 =
  3. 3.479 + 531 =
  4. 4.442 − 331 =
  5. 5.611 − 171 =
  6. 6.892 − 317 =
  7. 7.686 + 407 =
  8. 8.492 + 354 =
  9. 9.755 − 572 =
  10. 10.549 + 417 =
  11. 11.831 − 272 =
  12. 12.462 + 411 =
  13. 13.518 − 187 =
  14. 14.491 + 488 =
  15. 15.432 + 148 =
  16. 16.133 + 431 =
  17. 17.660 + 653 =
  18. 18.788 − 311 =
  19. 19.329 + 445 =
  20. 20.591 − 464 =
  21. 21.654 − 116 =
  22. 22.264 + 351 =
  23. 23.522 − 231 =
  24. 24.455 − 154 =
  25. 25.807 − 144 =
  26. 26.416 + 658 =
  27. 27.603 − 247 =
  28. 28.482 + 353 =
  29. 29.693 + 148 =
  30. 30.519 − 115 =
  31. 31.529 + 495 =
  32. 32.257 + 564 =
  33. 33.745 − 237 =
  34. 34.379 + 289 =
  35. 35.693 − 391 =
  36. 36.414 − 252 =
  37. 37.343 + 396 =
  38. 38.664 + 241 =
  39. 39.602 − 305 =
  40. 40.561 − 265 =

Answer key

  1. 398
  2. 219
  3. 1010
  4. 111
  5. 440
  6. 575
  7. 1093
  8. 846
  9. 183
  10. 966
  11. 559
  12. 873
  13. 331
  14. 979
  15. 580
  16. 564
  17. 1313
  18. 477
  19. 774
  20. 127
  21. 538
  22. 615
  23. 291
  24. 301
  25. 663
  26. 1074
  27. 356
  28. 835
  29. 841
  30. 404
  31. 1024
  32. 821
  33. 508
  34. 668
  35. 302
  36. 162
  37. 739
  38. 905
  39. 297
  40. 296

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