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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 4 · 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. 1.580 + 141 =
  2. 2.938 − 568 =
  3. 3.157 + 225 =
  4. 4.928 − 728 =
  5. 5.548 − 321 =
  6. 6.834 − 332 =
  7. 7.347 + 418 =
  8. 8.523 + 538 =
  9. 9.130 + 301 =
  10. 10.351 + 241 =
  11. 11.461 − 201 =
  12. 12.565 − 153 =
  13. 13.297 + 372 =
  14. 14.542 + 636 =
  15. 15.237 + 656 =
  16. 16.690 − 529 =
  17. 17.159 + 155 =
  18. 18.453 + 456 =
  19. 19.647 − 242 =
  20. 20.807 − 374 =
  21. 21.835 − 524 =
  22. 22.468 − 307 =
  23. 23.266 + 484 =
  24. 24.392 + 403 =
  25. 25.447 − 216 =
  26. 26.554 + 431 =
  27. 27.843 − 262 =
  28. 28.267 + 417 =
  29. 29.495 + 654 =
  30. 30.513 − 385 =
  31. 31.226 + 117 =
  32. 32.777 − 153 =
  33. 33.492 − 277 =
  34. 34.582 − 316 =
  35. 35.748 − 639 =
  36. 36.544 + 612 =
  37. 37.559 − 427 =
  38. 38.755 + 122 =
  39. 39.792 − 242 =
  40. 40.724 + 377 =

Answer key

  1. 721
  2. 370
  3. 382
  4. 200
  5. 227
  6. 502
  7. 765
  8. 1061
  9. 431
  10. 592
  11. 260
  12. 412
  13. 669
  14. 1178
  15. 893
  16. 161
  17. 314
  18. 909
  19. 405
  20. 433
  21. 311
  22. 161
  23. 750
  24. 795
  25. 231
  26. 985
  27. 581
  28. 684
  29. 1149
  30. 128
  31. 343
  32. 624
  33. 215
  34. 266
  35. 109
  36. 1156
  37. 132
  38. 877
  39. 550
  40. 1101

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