Perfect Number (film)
 Perfect Number (Hangul: 용의자X; RR: Yonguija X; lit. Suspect X) is a 2012 South Korean mystery-drama film directed by Bang Eun-jin. Adapted from Keigo Higashino's novel The Devotion of Suspect X it centers around a mild-mannered mathematics professor (Ryoo Seung-bum) who plans the perfect alibi for the woman he secretly loves (Lee Yo-won) when she unexpectedly murders her abusive ex-husband.