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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 638 · 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. 1.262 + 356 =
  2. 2.583 + 624 =
  3. 3.419 + 467 =
  4. 4.297 + 356 =
  5. 5.899 − 642 =
  6. 6.573 + 141 =
  7. 7.251 + 443 =
  8. 8.348 + 193 =
  9. 9.640 + 607 =
  10. 10.440 + 411 =
  11. 11.982 − 242 =
  12. 12.646 − 194 =
  13. 13.137 + 549 =
  14. 14.498 − 198 =
  15. 15.316 + 377 =
  16. 16.434 − 217 =
  17. 17.887 − 188 =
  18. 18.276 + 221 =
  19. 19.442 + 525 =
  20. 20.226 + 187 =
  21. 21.587 + 151 =
  22. 22.590 + 128 =
  23. 23.721 − 486 =
  24. 24.153 + 316 =
  25. 25.943 − 547 =
  26. 26.674 + 531 =
  27. 27.686 + 198 =
  28. 28.416 − 308 =
  29. 29.635 − 317 =
  30. 30.935 − 788 =
  31. 31.768 + 417 =
  32. 32.750 − 128 =
  33. 33.805 − 229 =
  34. 34.910 − 446 =
  35. 35.253 + 456 =
  36. 36.726 − 531 =
  37. 37.616 + 384 =
  38. 38.712 + 673 =
  39. 39.133 + 423 =
  40. 40.432 − 321 =

Answer key

  1. 618
  2. 1207
  3. 886
  4. 653
  5. 257
  6. 714
  7. 694
  8. 541
  9. 1247
  10. 851
  11. 740
  12. 452
  13. 686
  14. 300
  15. 693
  16. 217
  17. 699
  18. 497
  19. 967
  20. 413
  21. 738
  22. 718
  23. 235
  24. 469
  25. 396
  26. 1205
  27. 884
  28. 108
  29. 318
  30. 147
  31. 1185
  32. 622
  33. 576
  34. 464
  35. 709
  36. 195
  37. 1000
  38. 1385
  39. 556
  40. 111

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