Thursday, July 15, 2010

math fun

Well first non-math fun: try making s'mores with marshmallow peeps. Delicious!! The outer sugar crust caramelizes, doesn't catch fire like normal marshmallows, and leaves a crunchy sugar element. Plus you get to lobotomize dumb pink bunnies. This may be my most exciting invention yet...

And now the math fun. I saw this at the Exploratorium last month and it's incredibly simple, yet surprising at first glance.

Take any random sequence of digits. Choose any number between 1 and 9. Start at that number digit (if you picked 3, point to the 3rd digit). Now whatever that digit is, move that many digits forward, and repeat. Keep going a little way until you get bored.

Now choose a different digit between 1 and 9, and do the same thing. You'll almost certainly end up in the same place as the last time, after just a few steps!

It's surprising because we think of this as doing two independent things with random digits. But once you're on the path you already covered, you're stuck there forever since the sequence of digits is fixed, and in any step you have a 1 in 10 chance of landing on the previous path. Roll a ten sided dice a few times and you'll soon get the right number...

Well, I thought it was cool =)

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