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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 494 · 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. 1.820 − 398 =
  2. 2.665 + 155 =
  3. 3.874 − 378 =
  4. 4.919 − 404 =
  5. 5.491 − 137 =
  6. 6.270 + 171 =
  7. 7.502 − 145 =
  8. 8.329 + 648 =
  9. 9.481 + 155 =
  10. 10.676 + 488 =
  11. 11.691 + 162 =
  12. 12.207 + 248 =
  13. 13.501 − 298 =
  14. 14.313 + 341 =
  15. 15.615 + 217 =
  16. 16.186 + 611 =
  17. 17.477 + 434 =
  18. 18.184 + 611 =
  19. 19.450 + 398 =
  20. 20.893 − 631 =
  21. 21.662 − 219 =
  22. 22.404 + 166 =
  23. 23.728 − 485 =
  24. 24.404 + 171 =
  25. 25.829 − 177 =
  26. 26.493 − 244 =
  27. 27.950 − 129 =
  28. 28.480 + 455 =
  29. 29.856 − 664 =
  30. 30.794 − 448 =
  31. 31.563 + 488 =
  32. 32.748 + 548 =
  33. 33.271 + 218 =
  34. 34.676 + 576 =
  35. 35.666 + 246 =
  36. 36.778 − 678 =
  37. 37.675 − 143 =
  38. 38.241 + 347 =
  39. 39.174 + 507 =
  40. 40.548 + 259 =

Answer key

  1. 422
  2. 820
  3. 496
  4. 515
  5. 354
  6. 441
  7. 357
  8. 977
  9. 636
  10. 1164
  11. 853
  12. 455
  13. 203
  14. 654
  15. 832
  16. 797
  17. 911
  18. 795
  19. 848
  20. 262
  21. 443
  22. 570
  23. 243
  24. 575
  25. 652
  26. 249
  27. 821
  28. 935
  29. 192
  30. 346
  31. 1051
  32. 1296
  33. 489
  34. 1252
  35. 912
  36. 100
  37. 532
  38. 588
  39. 681
  40. 807

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