What are subtle ways to ask someone's age?

We've been flirting for a while and we even kissed once. He's from a different culture, so I don't know if it's inappropriate or not to ask him. Is there any subtle way to do it? I really like him, but I need to know his age, I don't want to get attached to him, and then realize that he's much older than me. Please help! Thanks!
What are subtle ways to ask someone's age?
Post Opinion