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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 373 · 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. 1.201 + 316 =
  2. 2.447 − 305 =
  3. 3.227 + 192 =
  4. 4.715 − 295 =
  5. 5.466 − 276 =
  6. 6.428 − 274 =
  7. 7.546 + 444 =
  8. 8.562 + 554 =
  9. 9.595 − 262 =
  10. 10.430 − 331 =
  11. 11.476 − 294 =
  12. 12.793 − 123 =
  13. 13.620 + 393 =
  14. 14.738 − 387 =
  15. 15.480 − 263 =
  16. 16.549 + 595 =
  17. 17.364 + 251 =
  18. 18.307 + 244 =
  19. 19.376 + 238 =
  20. 20.204 + 172 =
  21. 21.450 − 126 =
  22. 22.879 − 215 =
  23. 23.539 − 371 =
  24. 24.470 + 599 =
  25. 25.653 − 443 =
  26. 26.438 − 291 =
  27. 27.701 + 365 =
  28. 28.677 − 353 =
  29. 29.528 + 564 =
  30. 30.869 − 541 =
  31. 31.667 − 544 =
  32. 32.614 + 669 =
  33. 33.254 + 462 =
  34. 34.725 − 352 =
  35. 35.707 − 601 =
  36. 36.478 − 206 =
  37. 37.761 − 247 =
  38. 38.616 − 136 =
  39. 39.699 + 195 =
  40. 40.156 + 144 =

Answer key

  1. 517
  2. 142
  3. 419
  4. 420
  5. 190
  6. 154
  7. 990
  8. 1116
  9. 333
  10. 99
  11. 182
  12. 670
  13. 1013
  14. 351
  15. 217
  16. 1144
  17. 615
  18. 551
  19. 614
  20. 376
  21. 324
  22. 664
  23. 168
  24. 1069
  25. 210
  26. 147
  27. 1066
  28. 324
  29. 1092
  30. 328
  31. 123
  32. 1283
  33. 716
  34. 373
  35. 106
  36. 272
  37. 514
  38. 480
  39. 894
  40. 300

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