Alright, here's the problem. My birthday is July 25th. My brothers birthday is October 15th. I met a girl online about a year ago, and immedietaly noticed that her birthday, oddly enough, was October 15th. When I told her that she had my brothers birthday, she looked at my birthday (on my facebook account), and was stunned to see that my birthday is the same as HER brothers! The math problem: What are the chances of that happening? We can call me and my brother a and b, and her and her brother x and y. The chances of one person having any given birthday is 1 in 365. The number of combinations of any two days in the year, is 365 x 365. That's about as far as I can get. What are the chances and me and my brother share the exact same birthdays with this girl and her brother?