Question: Life of Kylie is an American reality television series starring Kylie Jenner,  best known for starring in the E! reality television series "Keeping Up with the Kardashians" since what young age?

Related documents: [0]  [DOC] Life of Kylie (LOK) is an American reality television series starring Kylie Jenner. The eight-part half-hour series premiered on August 6, 2017, on the E! cable network. The reality series was greenlit on April 10, 2017. On May 11, 2017, E! released the first promo video of the series. [END] 
[1]  [DOC] Kylie Kristen Jenner (born August 10, 1997) is an American reality television personality, model, entrepreneur, socialite, and social media personality. She is best known for starring in the E! reality television series "Keeping Up with the Kardashians" since age nine, her eponymous brand of cosmetics, and her large social media presence. [END]  
Answer: nine
nine