Convert from block [East U.S.] to royal foot

Unit Definition (block [East U.S.])
The Block is an informal unit of distance popular in the U.S. A block is the average distance between street intersections in the rectangular street grids common in most American cities. The length of a block in Eastern USA is about 1/20 mile or 80 meters.

Unit Definition (royal foot)
The royal foot is a French pied de roi, also called the Paris foot in English.