Another 'how to redirect' question

[IKatsu]

Can I use this to somehow add '&num=100' to google.com/search url's if there is no num= already in the url ?
I've been trying a few things bit Regex is black magic for me.

I have google.com and *.google.com as host with /search as path
'num' as exclude
and {href/$/?num=100} as a redirect action.