Convert from palmo [Spanish] to centimeter

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 (centimeter)
The centimeter (or centimetre) was the basic unit of distance in the former CGS (centimeter, gram, second) version of the metric system, equal to 0.01 meter. The engineering standard uses every third power of ten, such as 10e3, 10e9, 10e12, etc., and for small numbers 10e-3, 10e-6, etc. The only exception is the centimeter. "Cent" means a hundredth, or 10e-2, but the centimeter is still commonly used because it is such a convenient unit for measuring length.