Shell Script

I am not very good with shell scripting…I need a very short and simple script that requires a lot of CPU usage for a time of about 5 minutes.

I was thinking something like computing PI to x significant decimals(however many it would take to make this script run somewhere in that time-frame on my AIX box) That is just an idea. As long as it is CPU intensive and does not produce io, it doesn’t really matter what the script does. Thanks for any suggestions.