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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 281 · 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. 1.548 − 268 =
  2. 2.195 + 677 =
  3. 3.911 − 441 =
  4. 4.609 + 435 =
  5. 5.859 − 257 =
  6. 6.452 + 254 =
  7. 7.591 + 301 =
  8. 8.677 + 569 =
  9. 9.926 − 632 =
  10. 10.499 − 159 =
  11. 11.561 + 341 =
  12. 12.820 − 572 =
  13. 13.614 + 151 =
  14. 14.774 − 664 =
  15. 15.537 + 517 =
  16. 16.686 − 562 =
  17. 17.647 − 263 =
  18. 18.564 + 573 =
  19. 19.729 + 582 =
  20. 20.156 + 371 =
  21. 21.553 + 636 =
  22. 22.503 − 115 =
  23. 23.738 − 222 =
  24. 24.486 + 322 =
  25. 25.459 − 296 =
  26. 26.467 + 521 =
  27. 27.554 + 674 =
  28. 28.582 + 241 =
  29. 29.373 + 507 =
  30. 30.633 − 347 =
  31. 31.491 − 294 =
  32. 32.315 + 207 =
  33. 33.940 − 436 =
  34. 34.800 − 621 =
  35. 35.174 + 628 =
  36. 36.483 + 211 =
  37. 37.604 − 317 =
  38. 38.915 − 379 =
  39. 39.931 − 705 =
  40. 40.247 + 174 =

Answer key

  1. 280
  2. 872
  3. 470
  4. 1044
  5. 602
  6. 706
  7. 892
  8. 1246
  9. 294
  10. 340
  11. 902
  12. 248
  13. 765
  14. 110
  15. 1054
  16. 124
  17. 384
  18. 1137
  19. 1311
  20. 527
  21. 1189
  22. 388
  23. 516
  24. 808
  25. 163
  26. 988
  27. 1228
  28. 823
  29. 880
  30. 286
  31. 197
  32. 522
  33. 504
  34. 179
  35. 802
  36. 694
  37. 287
  38. 536
  39. 226
  40. 421

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