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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 160 · 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. 1.539 − 372 =
  2. 2.695 − 399 =
  3. 3.430 − 325 =
  4. 4.815 − 377 =
  5. 5.742 + 121 =
  6. 6.699 + 301 =
  7. 7.623 − 375 =
  8. 8.761 − 491 =
  9. 9.716 − 487 =
  10. 10.866 − 698 =
  11. 11.428 − 162 =
  12. 12.480 + 667 =
  13. 13.857 − 174 =
  14. 14.912 − 531 =
  15. 15.351 + 518 =
  16. 16.769 − 285 =
  17. 17.469 − 218 =
  18. 18.432 − 296 =
  19. 19.561 + 516 =
  20. 20.503 + 292 =
  21. 21.614 − 422 =
  22. 22.677 − 321 =
  23. 23.148 + 346 =
  24. 24.645 − 542 =
  25. 25.352 + 458 =
  26. 26.953 − 119 =
  27. 27.126 + 355 =
  28. 28.260 + 112 =
  29. 29.493 + 255 =
  30. 30.278 + 601 =
  31. 31.746 + 124 =
  32. 32.223 + 233 =
  33. 33.480 + 503 =
  34. 34.617 + 477 =
  35. 35.197 + 488 =
  36. 36.644 − 501 =
  37. 37.699 + 305 =
  38. 38.472 − 249 =
  39. 39.598 − 489 =
  40. 40.511 − 295 =

Answer key

  1. 167
  2. 296
  3. 105
  4. 438
  5. 863
  6. 1000
  7. 248
  8. 270
  9. 229
  10. 168
  11. 266
  12. 1147
  13. 683
  14. 381
  15. 869
  16. 484
  17. 251
  18. 136
  19. 1077
  20. 795
  21. 192
  22. 356
  23. 494
  24. 103
  25. 810
  26. 834
  27. 481
  28. 372
  29. 748
  30. 879
  31. 870
  32. 456
  33. 983
  34. 1094
  35. 685
  36. 143
  37. 1004
  38. 223
  39. 109
  40. 216

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