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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 894 · 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. 1.746 − 389 =
  2. 2.690 + 656 =
  3. 3.536 + 516 =
  4. 4.234 + 368 =
  5. 5.541 + 571 =
  6. 6.305 + 362 =
  7. 7.619 − 436 =
  8. 8.967 − 421 =
  9. 9.675 + 519 =
  10. 10.522 + 389 =
  11. 11.398 + 675 =
  12. 12.692 − 242 =
  13. 13.326 + 249 =
  14. 14.592 + 486 =
  15. 15.627 − 488 =
  16. 16.530 − 412 =
  17. 17.575 − 401 =
  18. 18.975 − 735 =
  19. 19.841 − 229 =
  20. 20.517 + 245 =
  21. 21.241 + 204 =
  22. 22.249 + 545 =
  23. 23.507 − 244 =
  24. 24.307 + 138 =
  25. 25.760 − 255 =
  26. 26.536 − 156 =
  27. 27.314 + 169 =
  28. 28.885 − 682 =
  29. 29.488 + 599 =
  30. 30.896 − 475 =
  31. 31.513 − 355 =
  32. 32.419 − 303 =
  33. 33.480 + 222 =
  34. 34.834 − 264 =
  35. 35.586 − 132 =
  36. 36.178 + 524 =
  37. 37.559 + 358 =
  38. 38.361 + 412 =
  39. 39.640 − 288 =
  40. 40.292 + 321 =

Answer key

  1. 357
  2. 1346
  3. 1052
  4. 602
  5. 1112
  6. 667
  7. 183
  8. 546
  9. 1194
  10. 911
  11. 1073
  12. 450
  13. 575
  14. 1078
  15. 139
  16. 118
  17. 174
  18. 240
  19. 612
  20. 762
  21. 445
  22. 794
  23. 263
  24. 445
  25. 505
  26. 380
  27. 483
  28. 203
  29. 1087
  30. 421
  31. 158
  32. 116
  33. 702
  34. 570
  35. 454
  36. 702
  37. 917
  38. 773
  39. 352
  40. 613

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