13^2

Numbers are fun.  They're like a huge puzzle that spans infinity.  Numbers are the real deal, and they're complex too (the jokes, the awful jokes).

This post is the 169th that I've published on the blog.  Because I'm a student of arithmetic, it means I know this is 13*13 posts.  And that is beautiful.  It might not mean anything, but that doesn't really matter.  The tiny puzzle that is identifying a number which can be factored as a square is delightful.

Here is another example of a lovely number puzzle that happened "recently."  May 12, 2013 was a day unlike most.  It can be written 5/12/13.  Maybe you're starting to catch on.
IT'S A PYTHAGOREAN TRIPLE!
That means that:

5*5 + 12*12 = 13*13

Alternately,

25 + 144 = 169 

...which is even cooler because this is my 169th post (no coincidence, I've been waiting for this moment).

It's also important to note that this year will have an epic PI day, though this is unrelated to days that are interesting arithmetically.  March 14, 2015 9:26.5359AM will be 3.14.15 9:26.5359 which is pretty cool.  These days just kind of exist, which doesn't constitute a tiny puzzle so much as a point in time (e.g. 11:11).

Be on the lookout for interesting numbered days though, the next Pythagorean Triple is in 2 years: (8, 15, 17).  It's a less obvious one to me, only because my functional knowledge of squares effectively ends at 15^2.

Maybe that means I need to brush up.