Wild About Math! Making Math fun and accessible

Fun calendar probability problem

I picked up a little gem from Math Wonders to Inspire Teachers and Students, by Alfred Posamentier. The book, by the way, is outstanding. Posamentier has become one of my heroes for writing books that awe and inspire students and teachers to get, well, Wild About Math! Someday I will review this, and other, outstanding books that make Math accessible and fun.

Here's the little problem:

What's the probability that 4/4, 6/6, 8/8, 10/10, and 12/12 all fall on the same day of the week?

It's fun to see what people come up with, especially if they give you an answer off the top of their heads.

A fun little exploration is why the answer is what it is. This exploration is a nice first step in doing calendar arithmetic.