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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 298 · 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. 1.229 + 648 =
  2. 2.714 + 242 =
  3. 3.524 + 172 =
  4. 4.727 + 468 =
  5. 5.527 − 385 =
  6. 6.558 − 438 =
  7. 7.222 + 597 =
  8. 8.706 − 336 =
  9. 9.958 − 212 =
  10. 10.691 + 274 =
  11. 11.272 + 634 =
  12. 12.663 − 148 =
  13. 13.830 − 201 =
  14. 14.516 + 334 =
  15. 15.510 + 686 =
  16. 16.310 + 668 =
  17. 17.764 + 439 =
  18. 18.497 − 211 =
  19. 19.772 − 445 =
  20. 20.422 − 158 =
  21. 21.739 + 447 =
  22. 22.415 + 272 =
  23. 23.853 − 379 =
  24. 24.522 − 221 =
  25. 25.792 − 157 =
  26. 26.444 − 209 =
  27. 27.584 − 204 =
  28. 28.782 − 666 =
  29. 29.273 + 584 =
  30. 30.853 − 285 =
  31. 31.513 + 617 =
  32. 32.868 − 363 =
  33. 33.444 + 266 =
  34. 34.468 − 153 =
  35. 35.264 + 271 =
  36. 36.678 + 227 =
  37. 37.637 + 261 =
  38. 38.790 − 522 =
  39. 39.756 + 276 =
  40. 40.523 − 276 =

Answer key

  1. 877
  2. 956
  3. 696
  4. 1195
  5. 142
  6. 120
  7. 819
  8. 370
  9. 746
  10. 965
  11. 906
  12. 515
  13. 629
  14. 850
  15. 1196
  16. 978
  17. 1203
  18. 286
  19. 327
  20. 264
  21. 1186
  22. 687
  23. 474
  24. 301
  25. 635
  26. 235
  27. 380
  28. 116
  29. 857
  30. 568
  31. 1130
  32. 505
  33. 710
  34. 315
  35. 535
  36. 905
  37. 898
  38. 268
  39. 1032
  40. 247

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