Calculator-1.12.1-5.0.0 is a release file of the Minecraft mod The Pentrahon, made for Minecraft 1.12.1. It was published on September 18, 2017 and is 1.4 MB in size. For the full description, screenshots and every other version, visit the The Pentrahon mod page.
How to install: Put the .jar into the mods folder (.minecraft/mods) and start Minecraft with the matching mod loader profile.