Why say numbers is free when it isn't

Only on new Macs that qualify.

Try the up to date program > https://www.apple.com/creativity-apps/mac/up-to-date/

Here > Apple - Up-to-Date Program for Pages, Numbers, and Keynote

my experience is that Numbers (and the other iWork applications) are free for any macintosh that is running OS X mavericks and later. Once you upgrade to Mavericks these applications will be available to install fro free from the App store. What version of the Mac OS are you running?