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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 100 · 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. 1.764 − 154 =
  2. 2.419 − 135 =
  3. 3.261 + 492 =
  4. 4.539 − 285 =
  5. 5.912 − 731 =
  6. 6.551 − 245 =
  7. 7.543 − 256 =
  8. 8.722 + 531 =
  9. 9.406 + 512 =
  10. 10.443 − 305 =
  11. 11.828 − 276 =
  12. 12.647 − 328 =
  13. 13.657 − 248 =
  14. 14.729 − 301 =
  15. 15.216 + 319 =
  16. 16.277 + 273 =
  17. 17.941 − 795 =
  18. 18.538 − 356 =
  19. 19.620 − 231 =
  20. 20.750 − 326 =
  21. 21.275 + 649 =
  22. 22.483 + 205 =
  23. 23.288 + 157 =
  24. 24.427 − 206 =
  25. 25.282 + 676 =
  26. 26.329 + 392 =
  27. 27.256 + 494 =
  28. 28.989 − 834 =
  29. 29.555 − 251 =
  30. 30.623 − 214 =
  31. 31.543 − 234 =
  32. 32.777 − 184 =
  33. 33.260 + 186 =
  34. 34.562 + 131 =
  35. 35.563 − 396 =
  36. 36.369 + 515 =
  37. 37.956 − 712 =
  38. 38.371 + 382 =
  39. 39.531 − 343 =
  40. 40.440 − 126 =

Answer key

  1. 610
  2. 284
  3. 753
  4. 254
  5. 181
  6. 306
  7. 287
  8. 1253
  9. 918
  10. 138
  11. 552
  12. 319
  13. 409
  14. 428
  15. 535
  16. 550
  17. 146
  18. 182
  19. 389
  20. 424
  21. 924
  22. 688
  23. 445
  24. 221
  25. 958
  26. 721
  27. 750
  28. 155
  29. 304
  30. 409
  31. 309
  32. 593
  33. 446
  34. 693
  35. 167
  36. 884
  37. 244
  38. 753
  39. 188
  40. 314

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