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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 37 · 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. 1.376 + 181 =
  2. 2.580 − 207 =
  3. 3.624 + 463 =
  4. 4.508 − 291 =
  5. 5.479 + 494 =
  6. 6.229 + 231 =
  7. 7.231 + 161 =
  8. 8.324 + 171 =
  9. 9.569 + 207 =
  10. 10.719 + 181 =
  11. 11.760 + 338 =
  12. 12.954 − 606 =
  13. 13.693 − 124 =
  14. 14.440 − 315 =
  15. 15.416 + 196 =
  16. 16.722 + 204 =
  17. 17.250 + 161 =
  18. 18.529 − 398 =
  19. 19.967 − 161 =
  20. 20.456 − 305 =
  21. 21.563 − 155 =
  22. 22.962 − 606 =
  23. 23.545 + 168 =
  24. 24.605 + 562 =
  25. 25.776 + 419 =
  26. 26.431 + 289 =
  27. 27.368 + 252 =
  28. 28.677 − 331 =
  29. 29.397 + 683 =
  30. 30.494 − 378 =
  31. 31.544 + 391 =
  32. 32.635 + 312 =
  33. 33.809 − 483 =
  34. 34.478 + 657 =
  35. 35.959 − 173 =
  36. 36.375 + 146 =
  37. 37.555 + 571 =
  38. 38.342 + 269 =
  39. 39.462 + 668 =
  40. 40.568 − 361 =

Answer key

  1. 557
  2. 373
  3. 1087
  4. 217
  5. 973
  6. 460
  7. 392
  8. 495
  9. 776
  10. 900
  11. 1098
  12. 348
  13. 569
  14. 125
  15. 612
  16. 926
  17. 411
  18. 131
  19. 806
  20. 151
  21. 408
  22. 356
  23. 713
  24. 1167
  25. 1195
  26. 720
  27. 620
  28. 346
  29. 1080
  30. 116
  31. 935
  32. 947
  33. 326
  34. 1135
  35. 786
  36. 521
  37. 1126
  38. 611
  39. 1130
  40. 207

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