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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 7 · 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. 1.305 + 132 =
  2. 2.804 − 397 =
  3. 3.224 + 271 =
  4. 4.487 − 258 =
  5. 5.511 + 301 =
  6. 6.538 − 155 =
  7. 7.700 + 431 =
  8. 8.281 + 477 =
  9. 9.909 − 617 =
  10. 10.849 − 297 =
  11. 11.596 − 461 =
  12. 12.539 − 386 =
  13. 13.925 − 282 =
  14. 14.599 + 139 =
  15. 15.487 + 609 =
  16. 16.849 − 319 =
  17. 17.217 + 424 =
  18. 18.947 − 833 =
  19. 19.878 − 246 =
  20. 20.467 − 186 =
  21. 21.593 − 139 =
  22. 22.241 + 576 =
  23. 23.763 + 199 =
  24. 24.694 + 605 =
  25. 25.551 + 569 =
  26. 26.457 − 325 =
  27. 27.753 − 431 =
  28. 28.631 + 332 =
  29. 29.869 − 646 =
  30. 30.192 + 246 =
  31. 31.518 + 551 =
  32. 32.594 − 203 =
  33. 33.255 + 167 =
  34. 34.518 − 314 =
  35. 35.748 + 549 =
  36. 36.704 − 181 =
  37. 37.149 + 401 =
  38. 38.292 + 171 =
  39. 39.450 − 213 =
  40. 40.452 + 222 =

Answer key

  1. 437
  2. 407
  3. 495
  4. 229
  5. 812
  6. 383
  7. 1131
  8. 758
  9. 292
  10. 552
  11. 135
  12. 153
  13. 643
  14. 738
  15. 1096
  16. 530
  17. 641
  18. 114
  19. 632
  20. 281
  21. 454
  22. 817
  23. 962
  24. 1299
  25. 1120
  26. 132
  27. 322
  28. 963
  29. 223
  30. 438
  31. 1069
  32. 391
  33. 422
  34. 204
  35. 1297
  36. 523
  37. 550
  38. 463
  39. 237
  40. 674

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