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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 526 · 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. 1.936 − 505 =
  2. 2.280 + 581 =
  3. 3.602 + 661 =
  4. 4.921 − 747 =
  5. 5.516 + 595 =
  6. 6.411 + 261 =
  7. 7.441 − 194 =
  8. 8.497 − 333 =
  9. 9.742 + 632 =
  10. 10.576 − 172 =
  11. 11.372 + 503 =
  12. 12.590 + 609 =
  13. 13.535 − 178 =
  14. 14.559 + 313 =
  15. 15.547 − 336 =
  16. 16.202 + 596 =
  17. 17.952 − 466 =
  18. 18.481 + 174 =
  19. 19.390 + 181 =
  20. 20.754 + 647 =
  21. 21.420 − 205 =
  22. 22.843 − 264 =
  23. 23.446 − 314 =
  24. 24.462 − 231 =
  25. 25.876 − 501 =
  26. 26.536 + 318 =
  27. 27.593 + 538 =
  28. 28.450 + 399 =
  29. 29.863 − 332 =
  30. 30.484 − 201 =
  31. 31.235 + 424 =
  32. 32.748 + 478 =
  33. 33.511 + 138 =
  34. 34.928 − 516 =
  35. 35.606 − 458 =
  36. 36.217 + 571 =
  37. 37.986 − 641 =
  38. 38.449 + 368 =
  39. 39.690 + 249 =
  40. 40.702 + 378 =

Answer key

  1. 431
  2. 861
  3. 1263
  4. 174
  5. 1111
  6. 672
  7. 247
  8. 164
  9. 1374
  10. 404
  11. 875
  12. 1199
  13. 357
  14. 872
  15. 211
  16. 798
  17. 486
  18. 655
  19. 571
  20. 1401
  21. 215
  22. 579
  23. 132
  24. 231
  25. 375
  26. 854
  27. 1131
  28. 849
  29. 531
  30. 283
  31. 659
  32. 1226
  33. 649
  34. 412
  35. 148
  36. 788
  37. 345
  38. 817
  39. 939
  40. 1080

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