that'll be the day!
Uncompressed digital 16 bit, stereo audio at 44.1 kHz will use 10.09 Mb of disk space for every minute of music, so a CD that has 74 minutes of music will occupy 747Mb of space - and that's without any gaps between tracks. It can get complicated because normal factory made CDs have redundant error correction code on them ( to deal with scratches etc) and that brings the available space down by a few %.
Your files, if they truly are 25Mb are certainly not full CDs, so that's the first thing to look at. I'm assuming you know that you can't write MP3 tracks (that you've downloaded) straight to a CD and expect to play it in a CD player - you must first convert the files to .wav format. The MP3 format compresses audio to around a tenth of the size of a .wav file, and I suspect that your files are MP3s.