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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 847 · 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. 1.811 − 324 =
  2. 2.412 − 153 =
  3. 3.546 − 231 =
  4. 4.511 − 224 =
  5. 5.496 + 526 =
  6. 6.861 − 618 =
  7. 7.527 − 175 =
  8. 8.264 + 211 =
  9. 9.416 − 145 =
  10. 10.491 + 535 =
  11. 11.142 + 309 =
  12. 12.262 + 591 =
  13. 13.484 − 351 =
  14. 14.503 + 162 =
  15. 15.556 − 136 =
  16. 16.794 − 518 =
  17. 17.707 + 687 =
  18. 18.407 + 435 =
  19. 19.124 + 435 =
  20. 20.495 − 146 =
  21. 21.664 − 172 =
  22. 22.343 + 169 =
  23. 23.609 − 237 =
  24. 24.721 − 517 =
  25. 25.869 − 591 =
  26. 26.672 − 572 =
  27. 27.459 − 197 =
  28. 28.386 + 366 =
  29. 29.236 + 203 =
  30. 30.715 + 675 =
  31. 31.352 + 323 =
  32. 32.500 + 231 =
  33. 33.433 − 276 =
  34. 34.515 − 291 =
  35. 35.232 + 357 =
  36. 36.642 − 171 =
  37. 37.908 − 163 =
  38. 38.519 − 404 =
  39. 39.138 + 491 =
  40. 40.426 − 325 =

Answer key

  1. 487
  2. 259
  3. 315
  4. 287
  5. 1022
  6. 243
  7. 352
  8. 475
  9. 271
  10. 1026
  11. 451
  12. 853
  13. 133
  14. 665
  15. 420
  16. 276
  17. 1394
  18. 842
  19. 559
  20. 349
  21. 492
  22. 512
  23. 372
  24. 204
  25. 278
  26. 100
  27. 262
  28. 752
  29. 439
  30. 1390
  31. 675
  32. 731
  33. 157
  34. 224
  35. 589
  36. 471
  37. 745
  38. 115
  39. 629
  40. 101

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