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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 426 · 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. 1.170 + 444 =
  2. 2.879 − 292 =
  3. 3.374 + 136 =
  4. 4.988 − 355 =
  5. 5.358 + 542 =
  6. 6.448 − 191 =
  7. 7.129 + 473 =
  8. 8.544 + 509 =
  9. 9.423 + 147 =
  10. 10.314 + 122 =
  11. 11.689 + 417 =
  12. 12.565 + 451 =
  13. 13.783 + 625 =
  14. 14.822 − 452 =
  15. 15.396 + 426 =
  16. 16.162 + 494 =
  17. 17.978 − 839 =
  18. 18.445 − 209 =
  19. 19.720 − 477 =
  20. 20.911 − 159 =
  21. 21.366 + 608 =
  22. 22.642 − 323 =
  23. 23.412 + 443 =
  24. 24.538 − 181 =
  25. 25.296 + 287 =
  26. 26.535 − 247 =
  27. 27.553 + 418 =
  28. 28.378 + 197 =
  29. 29.892 − 739 =
  30. 30.587 + 438 =
  31. 31.854 − 721 =
  32. 32.554 − 192 =
  33. 33.605 + 685 =
  34. 34.191 + 288 =
  35. 35.899 − 319 =
  36. 36.146 + 624 =
  37. 37.647 + 172 =
  38. 38.584 + 237 =
  39. 39.884 − 129 =
  40. 40.644 − 431 =

Answer key

  1. 614
  2. 587
  3. 510
  4. 633
  5. 900
  6. 257
  7. 602
  8. 1053
  9. 570
  10. 436
  11. 1106
  12. 1016
  13. 1408
  14. 370
  15. 822
  16. 656
  17. 139
  18. 236
  19. 243
  20. 752
  21. 974
  22. 319
  23. 855
  24. 357
  25. 583
  26. 288
  27. 971
  28. 575
  29. 153
  30. 1025
  31. 133
  32. 362
  33. 1290
  34. 479
  35. 580
  36. 770
  37. 819
  38. 821
  39. 755
  40. 213

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