3. (8 points) In another 12 days, it will be 2016, Hao Hao sighs: I have only experienced 2 leap years so far, and the year I was born is a multiple of 9, so in 2016, Hao Hao is $\qquad$ years old.
【Answer】Solution: Huhu has only experienced 2 leap years so far. Tracing back two leap years from 2015, they are 2012 and 2008,

so Huhu's birth year is between 2015 and 2004, among which the year that is a multiple of 9 is 2007, so Huhu was born in 2007,
$$
2016-2007=9 \text { (years old) }
$$

Answer: In 2016, Huhu is 9 years old.
Therefore, the answer is: 9.