Long story short an old friend and person I used to do a lot of business will be in town week after next. He is bringing his wife and two children. 1. I know the dates his kids were born. But I recall that Koreans don't decipher ages like we do in the west: Birth plus 365 day = 1 year old and so on. But more like a child is born 1 year old. Can someone explain this to me properly? And if this is close to correct is it an archaic practice? 2. At what age would it be appropriate to call a young Korean man, he's either 20 or 21 depending upon question 1, Mr. (insert Korean guy's first name)? Or is it better to refer to him simply by his first name as I'm pushing 30 years older than he? Any thoughts?