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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 622 · 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. 1.257 + 187 =
  2. 2.213 + 319 =
  3. 3.445 − 289 =
  4. 4.945 − 132 =
  5. 5.234 + 274 =
  6. 6.623 + 115 =
  7. 7.416 + 395 =
  8. 8.734 + 212 =
  9. 9.753 + 483 =
  10. 10.528 + 401 =
  11. 11.496 + 149 =
  12. 12.474 + 178 =
  13. 13.942 − 631 =
  14. 14.527 − 396 =
  15. 15.894 − 466 =
  16. 16.752 + 154 =
  17. 17.224 + 513 =
  18. 18.742 − 477 =
  19. 19.779 + 376 =
  20. 20.755 + 398 =
  21. 21.342 + 598 =
  22. 22.201 + 612 =
  23. 23.636 − 377 =
  24. 24.725 − 311 =
  25. 25.521 − 169 =
  26. 26.776 + 112 =
  27. 27.182 + 184 =
  28. 28.519 − 164 =
  29. 29.440 − 191 =
  30. 30.441 + 446 =
  31. 31.742 − 511 =
  32. 32.599 − 124 =
  33. 33.242 + 384 =
  34. 34.790 − 324 =
  35. 35.953 − 194 =
  36. 36.707 − 568 =
  37. 37.477 − 199 =
  38. 38.825 − 668 =
  39. 39.605 − 437 =
  40. 40.212 + 531 =

Answer key

  1. 444
  2. 532
  3. 156
  4. 813
  5. 508
  6. 738
  7. 811
  8. 946
  9. 1236
  10. 929
  11. 645
  12. 652
  13. 311
  14. 131
  15. 428
  16. 906
  17. 737
  18. 265
  19. 1155
  20. 1153
  21. 940
  22. 813
  23. 259
  24. 414
  25. 352
  26. 888
  27. 366
  28. 355
  29. 249
  30. 887
  31. 231
  32. 475
  33. 626
  34. 466
  35. 759
  36. 139
  37. 278
  38. 157
  39. 168
  40. 743

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