Without looking, how many pairs do we have on [our birthday] list?
A related question is graphed a short way into the same site cited above,
http://www.csicop.org/si/9809/coincidence.html

We need to know how many bridge hands have ever been dealt.
[picking a nit -e ] Perhaps we rather need to know how many bridge hands have ever been dealt to our board members or to people who subsequently had contact with our board members.