That was over 13 years ago in 2008.
Today he is 42, and has starred in 18 movies in total, 14 since 21 was released.
In 21, I think Aaron Yoo looks:
21 scores 6.5 out of 10 on The Movie Database.
Aaron Yoo's first acting role was as 'Ronnie' in Disturbia, released in 2007 when he was 27.