Manhattan address algorithm

The Manhattan address algorithm is a series of formulas used to estimate the closest east–west cross street for building numbers on north–south avenues in the New [York City] borough of Manhattan.

Algorithm

To find the approximate number of the closest cross street, divide the building number by a divisor and add the "tricky number" from the table below:
For the north–south avenues, there are typically 20 address numbers between consecutive east–west streets. A standard land lot on each avenue was originally 20 feet wide, and there is about between each pair of east–west streets, for ten land lots between each pair of streets. The exceptions are Riverside Drive, as well as Fifth Avenue and Central Park West between 59th and 110th streets, which use a divisor of 10. These avenues all have buildings only on one side of the street, with a park on the other side.
The "tricky number" often corresponds to a street near the southern end of the avenue. There are some notable exceptions:

York Avenue address numbers are continuations of Avenue A address numbers, since the avenue was originally called Avenue A.
East End Avenue address numbers are continuations of Avenue B address numbers, since the avenue was originally called Avenue B.
Sixth Avenue and Broadway start south of Houston Street, the southern boundary of the Manhattan street numbering system.
Although Park Avenue's southern terminus is at 32nd Street, a homeowner at 34th Street wanted the address "1 Park Avenue".

Examples

For example, if you are at 62 Avenue B,, then add the "tricky number" to give. The nearest cross street to 62 Avenue B is East 6th Street.
If you are at 78 Riverside Drive,, then add the "tricky number" to give. The nearest cross street to 78 Riverside Drive is West 80th Street.
If you are at 501 5th Avenue,, then add the "tricky number" to give. The nearest cross street to 501 5th Avenue is actually 42nd Street, not 43rd Street, as the Manhattan address algorithm only gives approximate answers.