Convert from zeptometer to block [Midwest U.S.]

Unit Definition (zeptometer)
The zeptometre (or zeptometer), symbol: zm, is an SI unit of metric length measurement. 1 zeptometre is 1e-21 metres, which is a very small distance

Unit Definition (block [Midwest 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 many midwestern USA cities is about 1/16 mile or 100 meters.