Simply replace the tag [random-number] by a random number.
[random-number from="2" to="72" format="%b"]%d minutes[/random-number]
output: an integer value between 2 & 72 followed by the word 'minutes'
This plugin is a sample on how to create a plugin which: * supports internationalization, * provides an option screen, * saves some options, * use images, * replaces a tag.
By the way, it generates randomized numbers ;o)
If you need more functionalities, feel free to ask (email/blog)...
A post with a French tutorial is available here.