Convert from yoctometer to mark twain

Unit Definition (yoctometer)
The yoctometre (or yoctometer), symbol: ym, is a decimal fraction of a metre, from the International System of Units. One yoctometre is 1x10-24 (1e-24) in scientific notation. Very small!

Unit Definition (mark twain)
The mark twain or twain is an old word for the number two, derived from the Anglo-Saxon twegen. The American author Samuel Clemens (1835-1910), who had been a riverboat pilot on the Mississippi in his youth, took his literary name from a traditional riverboat phrase "mark twain", meaning "exactly two" fathoms of water. This was the minimum depth needed for the boats to operate safely without running aground.