The category: TV biz events. The clue: King World fields 100,000 ticket requests to the festivities at Gotham’s Radio City Music Hall March 26. The answer: What is the 4,000th episode taping of hit gamer “Jeopardy?”

Radio City seats just 24,000 people, but “Jeopardy” showrunner Harry Friedman said the venue repped the largest turnout ever for a “Jeopardy” taping.

“We had more ushers (last week) than we do seats in our Culver City studio,” laughed Friedman, who celebrated the historic happening at a Radio City party that same night.

Friedman added, “one of the great things of having the taping at Radio City was that we were able to bring the show back to its roots.”

Before King World syndicated the show nationally in the mid-1980s, NBC broadcast “Jeopardy” from its studio in Rockefeller Center, which is just a couple of hundred feet away from Radio City.

Attendees of the taping received a Gotham-ized “Jeopardy” program, featuring a bio of host Alex Trebekand formatted in the style of a Broadway Playbill.

Those that missed seeing episode No. 4,000 live can catch it when it airs May 15. Also in May, “Jeopardy” will run its “Million Dollar Masters Tournament,” which taped March 24-26 at Radio City.