More numbers

After doing the math on the number of combinations for randomly generated passwords, I thought about TinyURL, a great service that’s been around for a long time. You enter any really long URL, and it creates a short one like http://tinyurl.com/XYZ that redirects to the original URL. It’s a pretty simple solution, but seems very cool nonetheless.

I’ve always wondered if they were going to run out of tiny URLs, until I did the math. Assuming 5 character URLs only made up of numbers and lowercase letters, they can create 60,466,176 URLs. Add uppercase letters and that’s 916,132,832 URLs. According to the website they have over 20 million URLs right now, so they have a way to go.

A slightly different math problem, in an episode of Thief last season, the main character was trying to crack a safe with a keypad. He used UV light or a spray or something to show which numbers had been pressed most frequently (don’t they do this in every safe cracking show?). There were four numbers used in the combination, and the safe had a defense mechanism where after three attempts you couldn’t enter any more combinations. This was supposed to add a lot of tension to the moment, but the main character was steadfast in his belief that he could guess the right combination.

I couldn’t help but do the math. There are only 24 possible combinations in this scenario, which sounds good at first, but that means you only have a 12.5% chance of getting the right combination before you’re stuck. If you’re playing Texas Hold’em, you have a better chance of beating a pair of aces preflop with kings, or even 3-2 offsuit. And you’ve got right about the same odds of cracking that safe as beating a pair of aces with 7-2 offsuit.

Maybe that just tells me I should be playing 3-2 offsuit more often.