Question: The series of poker tournaments sponsored by the corporation formerly known as "Harrah's entertainment" uses what playing cards as their official cards?
Sentence (from "World Series of Poker"): It dates its origins to 1970, when Benny Binion invited seven of the best-known poker players to the Horseshoe Casino for a single tournament, with a set start and stop time, and a winner determined by a secret ballot of the seven players.
Relevant evidence: No