Passage: At age four, Hannigan began appearing in commercials. She moved to Hollywood at age 11.Living with her mother and attending North Hollywood High School, she successfully auditioned for agents while visiting her father in Santa Barbara. After attending North Hollywood High School, she attended California State University, Northridge, where she was a member of the Alpha Chi Omega sorority and earned a degree in psychology.Hannigan's first major film role was in My Stepmother Is an Alien, a science-fiction comedy released in 1988; one of her co-stars in the film was actor Seth Green, who later joined her in the regular cast of Buffy as her on-screen boyfriend. In 1989, her first regular role on a TV series came when she was cast in the short-lived ABC sitcom Free Spirit. As a teenager, Hannigan babysat for the children of her future How I Met Your Mother costar, Bob Saget.

Question: what age did Hannigan go to Hollywood?
11