WordPress MU

The default number of posts that shows on the main page of a blog is 10. Some of my posts are too long and so the main page of my blog is really really long.

I read somewhere that there's a way where I can reduce the number of posts on the main page from 10 to 5 (or any number for that matter).

Can someone tell me where can I make the code change for that?

Thanks in advance.

Log in to the admin area, click 'options' then click 'reading' from the menus. There is an option there to change it.