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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 854 · 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. 1.902 − 239 =
  2. 2.804 − 213 =
  3. 3.601 − 381 =
  4. 4.895 − 261 =
  5. 5.921 − 308 =
  6. 6.515 − 399 =
  7. 7.478 + 296 =
  8. 8.470 + 137 =
  9. 9.361 + 131 =
  10. 10.485 − 319 =
  11. 11.786 − 485 =
  12. 12.713 − 365 =
  13. 13.827 − 371 =
  14. 14.588 − 397 =
  15. 15.609 + 361 =
  16. 16.902 − 794 =
  17. 17.724 − 425 =
  18. 18.245 + 131 =
  19. 19.129 + 175 =
  20. 20.841 − 476 =
  21. 21.652 + 688 =
  22. 22.449 + 321 =
  23. 23.587 + 428 =
  24. 24.309 + 606 =
  25. 25.327 + 125 =
  26. 26.481 − 187 =
  27. 27.711 + 178 =
  28. 28.859 − 474 =
  29. 29.380 + 202 =
  30. 30.580 − 321 =
  31. 31.592 + 492 =
  32. 32.691 − 114 =
  33. 33.403 + 513 =
  34. 34.449 − 272 =
  35. 35.438 − 124 =
  36. 36.879 − 579 =
  37. 37.178 + 134 =
  38. 38.403 + 426 =
  39. 39.409 + 434 =
  40. 40.557 − 235 =

Answer key

  1. 663
  2. 591
  3. 220
  4. 634
  5. 613
  6. 116
  7. 774
  8. 607
  9. 492
  10. 166
  11. 301
  12. 348
  13. 456
  14. 191
  15. 970
  16. 108
  17. 299
  18. 376
  19. 304
  20. 365
  21. 1340
  22. 770
  23. 1015
  24. 915
  25. 452
  26. 294
  27. 889
  28. 385
  29. 582
  30. 259
  31. 1084
  32. 577
  33. 916
  34. 177
  35. 314
  36. 300
  37. 312
  38. 829
  39. 843
  40. 322

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