Convert from dong [Vietnam] to mark twain

Unit Definition (dong [Vietnam])
The đồng (VND) is the standard unit of currency used in Vietnam. It has a symbol ₫. It is subdivided into 10 hào, which are divided into 10 xu. The hào and xu units of currency are so worthless that they are no longer issued.

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.