Hand (unit) divided by four, then the remainder is added after the radix point. Thus, a horse that measures 60 inches is 15 hands high (15 x 4 = 60) and a horse halfway between 15 and 16 hands is 15.2 hands, or 62 inches tall (15 x 4 + 2 = 62) Because the subdivision of a hand is a base 4 system, a horse 64 inches high is 16.0 hands high, not 15.4. A designation of "15.5 hands" is not halfway between 15 and 16 hands, but rather reads 15 hands and five inches, an impossibility in a base 4
Rack unit Rack unit A rack unit (abbreviated U or RU) is a unit of measure defined as . It is most frequently used as a measurement of the overall height of 19-inch and 23-inch rack frames, as well as the height of equipment that mounts in these frames, whereby the height of the frame or equipment is expressed as multiples of rack units. For example, a typical full-size rack cage is 42U high, while equipment is typically 1U, 2U, 3U, or 4U high. The rack unit size is based on a standard rack specification as defined in EIA-310. The Eurocard specifies