Today is, unofficially, Square Root Day (3/3/09). http://en.wikipedia.org/wiki/Square_root_day. The next Square Root Day will be April 4, 2016.
Before any stones are thrown 
…the tenuous connection to chess is that a chess board has a square root on it (8x8=64). Figured it needed a relation to chess, no matter how feeble.
I hope to be around for it, 8/8/64.
I doubt it though.
Well, let’s see. The last one was 5 years ago, the next one will be in 7 years, and the one after that will be another 9 years down the road. Is there a trend developing? 
If you really want a square root date then 4/5/2025 might be a possibility.
I thought I’d get that in before the thread was locked.
Er, I think that would be 5/5/2025… 
2025 = 45 squared.
Actually, that’s a theorem:
Squares: 0 1 4 9 16 25 36 49 64 81
Differences: 1 3 5 7 9 11 13 15 17
Bill Smythe
Bill, you are right. Since
(a + 1)2 - a = 2a + 1, so it doesn’t suprise me the difference between the squares of consecutive integers is an odd number.
Not only that, but 2a + 1 increases by 2 every time a increases by 1, thus proving not only that the differences are all odd, but also that they go up in arithmetic sequence, i.e. 1,3,5,7…
Bill Smythe