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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 831 · 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. 1.652 − 141 =
  2. 2.683 + 249 =
  3. 3.960 − 209 =
  4. 4.521 − 124 =
  5. 5.750 − 428 =
  6. 6.808 − 309 =
  7. 7.610 + 501 =
  8. 8.484 + 248 =
  9. 9.670 − 119 =
  10. 10.144 + 417 =
  11. 11.138 + 585 =
  12. 12.255 + 319 =
  13. 13.130 + 507 =
  14. 14.530 − 349 =
  15. 15.651 + 489 =
  16. 16.540 − 164 =
  17. 17.746 + 594 =
  18. 18.722 + 172 =
  19. 19.130 + 341 =
  20. 20.864 − 617 =
  21. 21.341 + 415 =
  22. 22.641 + 481 =
  23. 23.204 + 481 =
  24. 24.191 + 661 =
  25. 25.351 + 597 =
  26. 26.703 + 333 =
  27. 27.859 − 511 =
  28. 28.430 − 175 =
  29. 29.617 + 302 =
  30. 30.614 + 216 =
  31. 31.539 − 223 =
  32. 32.511 − 307 =
  33. 33.216 + 192 =
  34. 34.473 − 278 =
  35. 35.819 − 462 =
  36. 36.717 + 448 =
  37. 37.838 − 213 =
  38. 38.628 − 341 =
  39. 39.536 − 293 =
  40. 40.266 + 574 =

Answer key

  1. 511
  2. 932
  3. 751
  4. 397
  5. 322
  6. 499
  7. 1111
  8. 732
  9. 551
  10. 561
  11. 723
  12. 574
  13. 637
  14. 181
  15. 1140
  16. 376
  17. 1340
  18. 894
  19. 471
  20. 247
  21. 756
  22. 1122
  23. 685
  24. 852
  25. 948
  26. 1036
  27. 348
  28. 255
  29. 919
  30. 830
  31. 316
  32. 204
  33. 408
  34. 195
  35. 357
  36. 1165
  37. 625
  38. 287
  39. 243
  40. 840

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