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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 760 · 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. 1.808 − 563 =
  2. 2.502 − 263 =
  3. 3.768 + 461 =
  4. 4.626 − 512 =
  5. 5.219 + 359 =
  6. 6.535 + 484 =
  7. 7.967 − 303 =
  8. 8.569 − 391 =
  9. 9.915 − 276 =
  10. 10.579 + 308 =
  11. 11.967 − 804 =
  12. 12.573 − 313 =
  13. 13.736 + 291 =
  14. 14.548 − 115 =
  15. 15.268 + 119 =
  16. 16.171 + 464 =
  17. 17.417 − 152 =
  18. 18.522 + 668 =
  19. 19.585 + 255 =
  20. 20.344 + 313 =
  21. 21.599 + 571 =
  22. 22.314 + 561 =
  23. 23.445 − 144 =
  24. 24.845 − 578 =
  25. 25.797 − 369 =
  26. 26.841 − 371 =
  27. 27.595 − 246 =
  28. 28.910 − 622 =
  29. 29.163 + 569 =
  30. 30.725 + 194 =
  31. 31.768 + 135 =
  32. 32.181 + 237 =
  33. 33.225 + 518 =
  34. 34.418 + 661 =
  35. 35.527 + 624 =
  36. 36.195 + 508 =
  37. 37.864 − 519 =
  38. 38.713 − 221 =
  39. 39.923 − 413 =
  40. 40.203 + 193 =

Answer key

  1. 245
  2. 239
  3. 1229
  4. 114
  5. 578
  6. 1019
  7. 664
  8. 178
  9. 639
  10. 887
  11. 163
  12. 260
  13. 1027
  14. 433
  15. 387
  16. 635
  17. 265
  18. 1190
  19. 840
  20. 657
  21. 1170
  22. 875
  23. 301
  24. 267
  25. 428
  26. 470
  27. 349
  28. 288
  29. 732
  30. 919
  31. 903
  32. 418
  33. 743
  34. 1079
  35. 1151
  36. 703
  37. 345
  38. 492
  39. 510
  40. 396

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