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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 650 · 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. 1.534 − 201 =
  2. 2.652 − 341 =
  3. 3.503 + 325 =
  4. 4.789 − 407 =
  5. 5.501 + 369 =
  6. 6.242 + 535 =
  7. 7.306 + 151 =
  8. 8.353 + 538 =
  9. 9.368 + 493 =
  10. 10.546 + 284 =
  11. 11.829 − 559 =
  12. 12.743 + 606 =
  13. 13.595 + 432 =
  14. 14.865 − 146 =
  15. 15.649 + 628 =
  16. 16.867 − 221 =
  17. 17.607 + 681 =
  18. 18.294 + 653 =
  19. 19.324 + 622 =
  20. 20.425 − 177 =
  21. 21.655 + 373 =
  22. 22.531 − 237 =
  23. 23.360 + 191 =
  24. 24.245 + 434 =
  25. 25.416 − 121 =
  26. 26.479 − 151 =
  27. 27.400 + 215 =
  28. 28.242 + 155 =
  29. 29.625 + 534 =
  30. 30.315 + 121 =
  31. 31.458 + 317 =
  32. 32.591 + 264 =
  33. 33.168 + 165 =
  34. 34.714 − 544 =
  35. 35.231 + 538 =
  36. 36.761 + 335 =
  37. 37.198 + 258 =
  38. 38.150 + 676 =
  39. 39.704 + 625 =
  40. 40.578 + 316 =

Answer key

  1. 333
  2. 311
  3. 828
  4. 382
  5. 870
  6. 777
  7. 457
  8. 891
  9. 861
  10. 830
  11. 270
  12. 1349
  13. 1027
  14. 719
  15. 1277
  16. 646
  17. 1288
  18. 947
  19. 946
  20. 248
  21. 1028
  22. 294
  23. 551
  24. 679
  25. 295
  26. 328
  27. 615
  28. 397
  29. 1159
  30. 436
  31. 775
  32. 855
  33. 333
  34. 170
  35. 769
  36. 1096
  37. 456
  38. 826
  39. 1329
  40. 894

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