Convert from span to sadzhen

Unit Definition (span)
Span is the width of a human hand, from the tip of the thumb to the tip of the pinky finger.

Unit Definition (sadzhen)
The sadzhen is a traditional Russian unit of distance corresponding roughly to the English fathom and French toise. Early in the 1700s, Czar Peter the Great fixed the length of the sadzhen at exactly 7 English feet. This equals 3 arshin or 2.1336 meters. Sagene is an older transliteration of the Russian word.