RubyMoney/money — pull request #237 by cathper (2013-01-02 10:13:26+00:00)
Title: Add exponent to currency

The exponent of a money value is the number of digits after the decimal separator (that separates the major unit from the minor unit). See e.g. Section http://en.wikipedia.org/wiki/ISO_4217#Code_formation and the tables.

It's just the simple method Money::Currency#exponent that does the logarithmic calculation.