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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 740 · 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. 1.347 + 493 =
  2. 2.580 − 185 =
  3. 3.672 + 688 =
  4. 4.653 − 536 =
  5. 5.313 + 223 =
  6. 6.541 + 428 =
  7. 7.761 + 135 =
  8. 8.600 + 373 =
  9. 9.588 + 498 =
  10. 10.749 + 591 =
  11. 11.939 − 799 =
  12. 12.583 + 391 =
  13. 13.527 − 122 =
  14. 14.129 + 515 =
  15. 15.900 − 532 =
  16. 16.748 + 212 =
  17. 17.478 − 167 =
  18. 18.365 + 387 =
  19. 19.633 + 499 =
  20. 20.753 − 527 =
  21. 21.473 − 139 =
  22. 22.758 + 467 =
  23. 23.461 − 171 =
  24. 24.841 − 326 =
  25. 25.574 − 435 =
  26. 26.159 + 512 =
  27. 27.476 − 118 =
  28. 28.974 − 731 =
  29. 29.388 + 525 =
  30. 30.400 + 463 =
  31. 31.940 − 361 =
  32. 32.172 + 658 =
  33. 33.263 + 307 =
  34. 34.543 + 526 =
  35. 35.611 − 277 =
  36. 36.715 − 166 =
  37. 37.664 − 155 =
  38. 38.926 − 551 =
  39. 39.716 − 448 =
  40. 40.431 + 416 =

Answer key

  1. 840
  2. 395
  3. 1360
  4. 117
  5. 536
  6. 969
  7. 896
  8. 973
  9. 1086
  10. 1340
  11. 140
  12. 974
  13. 405
  14. 644
  15. 368
  16. 960
  17. 311
  18. 752
  19. 1132
  20. 226
  21. 334
  22. 1225
  23. 290
  24. 515
  25. 139
  26. 671
  27. 358
  28. 243
  29. 913
  30. 863
  31. 579
  32. 830
  33. 570
  34. 1069
  35. 334
  36. 549
  37. 509
  38. 375
  39. 268
  40. 847

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