Fan Casting Pi (1977)

Numbers whiz Max Cohen is stunted by psychological delusions of paranoia and debilitating headaches. He lives in a messy Chinatown apartment, where he tinkers with equations and his homemade, super-advanced computer. One day, however, Cohen encounters a mysterious number. Soon after reporting his discovery to his mentor and to a religious friend, he finds himself the target of ill-intentioned Wall Street agents bent on using the number for profit.