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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 468 · 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. 1.616 − 213 =
  2. 2.431 − 231 =
  3. 3.727 + 641 =
  4. 4.662 + 651 =
  5. 5.405 + 136 =
  6. 6.123 + 214 =
  7. 7.469 − 146 =
  8. 8.517 + 643 =
  9. 9.470 − 218 =
  10. 10.579 − 245 =
  11. 11.863 − 671 =
  12. 12.197 + 594 =
  13. 13.615 + 171 =
  14. 14.447 − 189 =
  15. 15.928 − 192 =
  16. 16.317 + 264 =
  17. 17.802 − 342 =
  18. 18.750 + 341 =
  19. 19.901 − 481 =
  20. 20.158 + 145 =
  21. 21.431 − 286 =
  22. 22.725 − 421 =
  23. 23.776 − 592 =
  24. 24.789 + 526 =
  25. 25.197 + 136 =
  26. 26.702 + 511 =
  27. 27.497 + 438 =
  28. 28.167 + 158 =
  29. 29.250 + 345 =
  30. 30.803 − 468 =
  31. 31.989 − 866 =
  32. 32.815 − 638 =
  33. 33.693 + 561 =
  34. 34.633 − 187 =
  35. 35.552 + 394 =
  36. 36.827 − 656 =
  37. 37.277 + 207 =
  38. 38.159 + 272 =
  39. 39.632 + 171 =
  40. 40.611 − 211 =

Answer key

  1. 403
  2. 200
  3. 1368
  4. 1313
  5. 541
  6. 337
  7. 323
  8. 1160
  9. 252
  10. 334
  11. 192
  12. 791
  13. 786
  14. 258
  15. 736
  16. 581
  17. 460
  18. 1091
  19. 420
  20. 303
  21. 145
  22. 304
  23. 184
  24. 1315
  25. 333
  26. 1213
  27. 935
  28. 325
  29. 595
  30. 335
  31. 123
  32. 177
  33. 1254
  34. 446
  35. 946
  36. 171
  37. 484
  38. 431
  39. 803
  40. 400

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