They never trailed, scored on 22 of their first 26 possessions, led by 30 and cruised into the semifinals by avenging their first loss this season.
Ralston Turner had 16 points and Abdul-Malik Abu added 10 for the seventh-seeded Wolfpack (20-13).
One night earlier, they beat Pittsburgh in the second round for their third straight win.
But key guard Anthony "Cat" Barber -- who had 34 points against Pitt -- was scoreless, missed seven shots and never returned after he was shaken up in a collision with Amile Jefferson with 13:26 left.
Trevor Lacey, who had 21 points last time against Duke, managed just four on 2-of-7 shooting.
Justise Winslow, Matt Jones and Grayson Allen had 11 points each while ACC player of the year Jahlil Okafor added 10 for Duke, which will play either No. 11 Notre Dame or Miami on Friday night in the semifinals.
The Blue Devils last played as the nation's second-ranked team on Jan. 11 -- when they limped out of Raleigh with an 87-75 loss to N.C. State.
With Duke clicking like this, there was no chance of that happening again.
There was no shortage of highlights for the Blue Devils during a stretch of 18 1/2 minutes in which N.C. State managed just four defensive stops.
Plumlee had two alley-oop dunks. Jones buried a corner 3 with a hand in his face. Cook fumbled the ball while on the run, but recovered in time to bury a 3 of his own in the other corner.
By the time Allen swished a 3 with 90 seconds left, Duke led 49-20 and it was effectively over.
N.C. State: This was easily the worst loss of the season for Wolfpack, who hadn't been beaten by more than 16 points (Cincinnati, Boston College).
Duke: Tyus Jones had eight assists. ... The Blue Devils' current winning streak is their fifth of at least 10 games during this decade.
N.C. State: NCAA Tournament.
Duke: Plays either No. 11 Notre Dame or Miami on Friday night in the semifinals.