Convert from palmo [Spanish] to story

Unit Definition (palmo [Spanish])
The palmo is a traditional unit of distance in Spain and Portugal. The traditional Spanish palmo equals 9 pulgadas or 1/4 vara: this is about 20.9 centimeters in Spain and a little more than that in Spanish Latin America. Under the metric system in Spain, the palmo is an informal unit equal to 20 centimeters. These units are based on the width of a person's outstretched hand, from the tip of the thumb to the tip of the little finger, a definition identical to that of the English span.

Unit Definition (story)
The story is an informal unit of distance equal to the average distance between floors of a building. In British English the spelling is "storey" and the plural is "storeys"; Americans write "story" and "stories." Typically a story equals 10 to 12 feet (3.0-3.6 meters). The origin of this use of the word "story" is not entirely clear, but in medieval times a tier of sculptures or stained glass windows on the front of a cathedral was called a stor(e)y because it usually told a story, and the number of stories was a measure of the size of the building.