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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 109 · 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. 1.251 + 282 =
  2. 2.756 − 241 =
  3. 3.508 + 332 =
  4. 4.964 − 746 =
  5. 5.233 + 266 =
  6. 6.576 − 243 =
  7. 7.585 − 201 =
  8. 8.550 + 581 =
  9. 9.678 + 201 =
  10. 10.696 − 322 =
  11. 11.368 + 171 =
  12. 12.721 − 604 =
  13. 13.613 − 158 =
  14. 14.549 + 508 =
  15. 15.710 + 326 =
  16. 16.597 + 249 =
  17. 17.421 + 167 =
  18. 18.730 − 532 =
  19. 19.649 + 227 =
  20. 20.331 + 499 =
  21. 21.213 + 684 =
  22. 22.144 + 648 =
  23. 23.749 + 306 =
  24. 24.149 + 276 =
  25. 25.412 + 487 =
  26. 26.852 − 447 =
  27. 27.629 + 595 =
  28. 28.857 − 511 =
  29. 29.364 + 651 =
  30. 30.587 − 195 =
  31. 31.714 − 202 =
  32. 32.878 − 282 =
  33. 33.949 − 261 =
  34. 34.679 + 189 =
  35. 35.460 − 171 =
  36. 36.408 + 131 =
  37. 37.762 + 369 =
  38. 38.941 − 146 =
  39. 39.588 − 461 =
  40. 40.305 + 135 =

Answer key

  1. 533
  2. 515
  3. 840
  4. 218
  5. 499
  6. 333
  7. 384
  8. 1131
  9. 879
  10. 374
  11. 539
  12. 117
  13. 455
  14. 1057
  15. 1036
  16. 846
  17. 588
  18. 198
  19. 876
  20. 830
  21. 897
  22. 792
  23. 1055
  24. 425
  25. 899
  26. 405
  27. 1224
  28. 346
  29. 1015
  30. 392
  31. 512
  32. 596
  33. 688
  34. 868
  35. 289
  36. 539
  37. 1131
  38. 795
  39. 127
  40. 440

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