a good algo to do this

[eight02645999 at yahoo.com]

hi
i need to do something like this
eg given a number (as a string) = "123"
there are a few combination i want to find with this string, ie
"132","321","231","312" and "213". so there are 6 combinations
altogether. i remember there's a formula for this, but forgot. Does
python have any modules/functions to do this?

thanks