5. (10 points) In another 12 days, it will be 2016, HaoHao sighs: I have only experienced 2 leap years so far, and the year I was born is a multiple of 9. So, how old will HaoHao be in 2016? $\qquad$ years old.
【Answer】Solution: Hao Hao has only experienced 2 leap years so far. Tracing back two leap years from 2015, they are 2012 and 2008,

so Hao Hao's birth year is between 2015 and 2004, and the year that is a multiple of 9 within this range is 2007,
therefore, Hao Hao was born in 2007,
$2016-2007=9$ (years old)
Answer: In 2016, Hao Hao is 9 years old.
Therefore, the answer is: 9.