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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 548 · 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. 1.722 − 478 =
  2. 2.520 − 341 =
  3. 3.540 − 125 =
  4. 4.913 − 251 =
  5. 5.577 + 433 =
  6. 6.651 + 179 =
  7. 7.689 − 274 =
  8. 8.468 − 264 =
  9. 9.897 − 475 =
  10. 10.706 − 196 =
  11. 11.920 − 812 =
  12. 12.956 − 585 =
  13. 13.668 + 369 =
  14. 14.603 − 399 =
  15. 15.247 + 201 =
  16. 16.911 − 455 =
  17. 17.434 − 142 =
  18. 18.865 − 452 =
  19. 19.450 − 298 =
  20. 20.707 − 482 =
  21. 21.415 − 309 =
  22. 22.571 + 433 =
  23. 23.296 + 213 =
  24. 24.549 − 382 =
  25. 25.580 + 457 =
  26. 26.414 − 233 =
  27. 27.734 + 358 =
  28. 28.500 − 233 =
  29. 29.633 + 204 =
  30. 30.558 − 198 =
  31. 31.306 + 139 =
  32. 32.515 − 179 =
  33. 33.482 + 599 =
  34. 34.165 + 151 =
  35. 35.767 + 447 =
  36. 36.921 − 291 =
  37. 37.646 − 364 =
  38. 38.176 + 688 =
  39. 39.439 − 279 =
  40. 40.557 + 296 =

Answer key

  1. 244
  2. 179
  3. 415
  4. 662
  5. 1010
  6. 830
  7. 415
  8. 204
  9. 422
  10. 510
  11. 108
  12. 371
  13. 1037
  14. 204
  15. 448
  16. 456
  17. 292
  18. 413
  19. 152
  20. 225
  21. 106
  22. 1004
  23. 509
  24. 167
  25. 1037
  26. 181
  27. 1092
  28. 267
  29. 837
  30. 360
  31. 445
  32. 336
  33. 1081
  34. 316
  35. 1214
  36. 630
  37. 282
  38. 864
  39. 160
  40. 853

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