Hour

Hour is a unit of time measurement on Tetro under the Uniform Subdivision system, abbreviated as hr in Tetrian English. There are 81 hours in one Tetrian day (a full rotation of the planet on its vertical axis), numbered from 0hr to 80hr. In relation to Earth time, one hour is about 53 Earth-minutes or 0.8953 Earth-hours.

A division of 81 hours was chosen so that in Tetrian, each hour can be represented by a 4-digit number. For example:

0hr = 0000gil

25hr = 0221gil

80hr = 2222gil