Lost Movie

I remember an old movie (B&W?). A man ironing (Mr. Belvedere?-Clifton Webb?), is watching a game show and says he can do better. So he goes on the show dressed as an Encyclopedia, which means the host can ask any question. Each week the prize doubles if the answer is correct. The contestant can then chose to come back and do double or nothing. The week before he would end up owning the TV station, he secretly agrees to lose, for a new car and money? So the host asks for his wallet and then what is his Social Security number? He "loses"

Anyone know what the name of this movie is?

FOUND IT: Champagne for Caesar 1950. The character of Beauregard Bottomley reminds me of Mr Belvedere.