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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 727 · 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. 1.434 − 172 =
  2. 2.772 + 288 =
  3. 3.889 − 272 =
  4. 4.198 + 445 =
  5. 5.375 + 187 =
  6. 6.553 − 241 =
  7. 7.398 + 261 =
  8. 8.735 + 447 =
  9. 9.494 − 221 =
  10. 10.274 + 212 =
  11. 11.638 − 239 =
  12. 12.286 + 411 =
  13. 13.689 + 671 =
  14. 14.790 − 125 =
  15. 15.484 − 173 =
  16. 16.283 + 186 =
  17. 17.728 − 236 =
  18. 18.538 − 139 =
  19. 19.398 + 549 =
  20. 20.472 + 133 =
  21. 21.425 − 183 =
  22. 22.297 + 294 =
  23. 23.626 − 142 =
  24. 24.349 + 431 =
  25. 25.878 − 471 =
  26. 26.955 − 505 =
  27. 27.707 − 121 =
  28. 28.173 + 434 =
  29. 29.745 − 405 =
  30. 30.266 + 295 =
  31. 31.856 − 538 =
  32. 32.572 + 221 =
  33. 33.727 − 304 =
  34. 34.611 + 551 =
  35. 35.416 + 153 =
  36. 36.805 − 139 =
  37. 37.366 + 604 =
  38. 38.647 − 195 =
  39. 39.501 − 117 =
  40. 40.335 + 212 =

Answer key

  1. 262
  2. 1060
  3. 617
  4. 643
  5. 562
  6. 312
  7. 659
  8. 1182
  9. 273
  10. 486
  11. 399
  12. 697
  13. 1360
  14. 665
  15. 311
  16. 469
  17. 492
  18. 399
  19. 947
  20. 605
  21. 242
  22. 591
  23. 484
  24. 780
  25. 407
  26. 450
  27. 586
  28. 607
  29. 340
  30. 561
  31. 318
  32. 793
  33. 423
  34. 1162
  35. 569
  36. 666
  37. 970
  38. 452
  39. 384
  40. 547

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