US dollar to Mexican peso and back (USD/MXN)

A factor of a thousand. MXP was the peso before 1993; on 1 January of that year one new peso was set equal to a thousand old ones and the code became MXN. During the changeover the notes carried N$ to mark it. A price read in an earlier document is divided by a thousand before it is converted.

By the country, or by the code, never by the sign: both use the same character. In Mexico a price marked with that sign is in pesos unless stated otherwise, and when the two must be told apart MX$ is written against US$.