[gentoo-user] OT Best way to compress files with digits

Hi,

 I have a lot of files with digits of PI. The digits
 are the characters of 0-9. Currently they are ZIPped,
 which I think is not the best way to do that.

 I read of 7zips PPMd which compresses "natural text"
 quite well...but my files are not "natural text" (as
 they are also no "binary data").

 With what practical way of compression is it possible
 to compress the files (file by file) as much as possible?

 Thank you very much in advance for any help!

 Best regards,
 mcc