## Archive for April 15, 2010

### Tax Day

Income tax is due today. Here’s a good, clean joke for April 15:

A nickel rolled down the hill. Why didn’t the quarter follow her?

Because it had too much cents!

### April 15 is National High Five Day

The third Thursday of April is National High Five Day. In 2010, that’s today! Normally, I ignore made up holidays like this, but there are (at least) two great math problems that involve high fives. So if acknowledging a silly fabrication means I get to share some math, then I’m all for it.

Here are the problems I know related to high fives:

There are five players on a basketball team. When the star player hit the winning free throw at the end of regulation, she and each of her teammates gave each other a high five. How many high fives occurred?

You could also ask this question in the opposite direction (though it’s really the same question):

My friends and I were watching a Penn State football game. When Penn State kicked the winning field, my friends and I gave each other high fives. Each friend gave exactly one high five to every other friend. A total of 36 high fives occurred. How many friends were watching the game with me?

But, in my opinion, here is the best variation of this problem:

My wife and I play on a softball team with four other couples. After I hit the game-winning home run at a recent game, a lot of high fives occurred among the players on our team. But not everyone got a high five from everyone else, no one got a high five from his or her spouse, and — obviously — no one high fived himself. Later, I asked each of my teammates how many high fives they received, and everyone gave me a different response. How many high fives did my wife get?

Now, don’t you agree that those questions make celebrating National High Five Day a reasonable thing to do?