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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 845 · 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. 1.411 + 146 =
  2. 2.478 − 211 =
  3. 3.442 − 191 =
  4. 4.641 + 123 =
  5. 5.487 − 148 =
  6. 6.442 − 221 =
  7. 7.528 − 423 =
  8. 8.858 − 323 =
  9. 9.516 − 253 =
  10. 10.813 − 584 =
  11. 11.204 + 524 =
  12. 12.582 + 121 =
  13. 13.747 − 421 =
  14. 14.190 + 562 =
  15. 15.402 + 562 =
  16. 16.440 − 243 =
  17. 17.506 + 467 =
  18. 18.627 − 151 =
  19. 19.920 − 764 =
  20. 20.664 + 587 =
  21. 21.675 + 363 =
  22. 22.843 − 531 =
  23. 23.430 − 171 =
  24. 24.749 − 175 =
  25. 25.666 + 581 =
  26. 26.740 + 498 =
  27. 27.519 + 378 =
  28. 28.496 + 261 =
  29. 29.743 − 302 =
  30. 30.395 + 282 =
  31. 31.531 + 514 =
  32. 32.703 + 151 =
  33. 33.668 + 359 =
  34. 34.792 − 484 =
  35. 35.539 − 149 =
  36. 36.310 + 161 =
  37. 37.617 − 334 =
  38. 38.948 − 615 =
  39. 39.418 − 236 =
  40. 40.226 + 512 =

Answer key

  1. 557
  2. 267
  3. 251
  4. 764
  5. 339
  6. 221
  7. 105
  8. 535
  9. 263
  10. 229
  11. 728
  12. 703
  13. 326
  14. 752
  15. 964
  16. 197
  17. 973
  18. 476
  19. 156
  20. 1251
  21. 1038
  22. 312
  23. 259
  24. 574
  25. 1247
  26. 1238
  27. 897
  28. 757
  29. 441
  30. 677
  31. 1045
  32. 854
  33. 1027
  34. 308
  35. 390
  36. 471
  37. 283
  38. 333
  39. 182
  40. 738

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