Regardless of the specific interpretation, the "100" represents completeness and scale. It is the platform’s promise that you are not getting fragmented, low-effort content, but rather a full-spectrum learning experience.
For a site that has existed for nearly a decade, it has a relatively low popularity ranking, which can sometimes be a sign that the site is highly specialized or serves a niche community (like gamers looking for cheats). Megatut.com 100