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?
Facts:
Life of Kylie is an American reality television series
Life of Kylie stars Kylie Jenner
Kylie Jenner is best known for starring in the E! reality television series "Keeping Up with the Kardashians" since age nine
Answer: nine