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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 475 · 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. 1.791 − 391 =
  2. 2.584 − 458 =
  3. 3.444 + 661 =
  4. 4.546 − 341 =
  5. 5.734 + 277 =
  6. 6.545 + 642 =
  7. 7.877 − 135 =
  8. 8.495 − 237 =
  9. 9.221 + 154 =
  10. 10.464 − 138 =
  11. 11.757 + 585 =
  12. 12.635 + 546 =
  13. 13.428 + 342 =
  14. 14.625 − 264 =
  15. 15.680 − 319 =
  16. 16.591 + 137 =
  17. 17.768 − 593 =
  18. 18.147 + 212 =
  19. 19.659 − 525 =
  20. 20.581 − 255 =
  21. 21.727 + 341 =
  22. 22.759 − 635 =
  23. 23.624 − 162 =
  24. 24.220 + 672 =
  25. 25.638 + 289 =
  26. 26.380 + 596 =
  27. 27.645 − 114 =
  28. 28.443 − 115 =
  29. 29.277 + 583 =
  30. 30.335 + 633 =
  31. 31.459 + 504 =
  32. 32.695 + 166 =
  33. 33.589 − 303 =
  34. 34.258 + 158 =
  35. 35.942 − 565 =
  36. 36.720 − 356 =
  37. 37.766 + 295 =
  38. 38.622 + 153 =
  39. 39.629 − 208 =
  40. 40.711 + 512 =

Answer key

  1. 400
  2. 126
  3. 1105
  4. 205
  5. 1011
  6. 1187
  7. 742
  8. 258
  9. 375
  10. 326
  11. 1342
  12. 1181
  13. 770
  14. 361
  15. 361
  16. 728
  17. 175
  18. 359
  19. 134
  20. 326
  21. 1068
  22. 124
  23. 462
  24. 892
  25. 927
  26. 976
  27. 531
  28. 328
  29. 860
  30. 968
  31. 963
  32. 861
  33. 286
  34. 416
  35. 377
  36. 364
  37. 1061
  38. 775
  39. 421
  40. 1223

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