noun For a number x, the exponent by which a given base number must be raised in order to obtain the power x. Written logbx. For example, log101000=3 because 103=1000 and log216=4 because 24=16.
For a currency which uses denominations of 1, 2, 5, 10, 20, 50, 100, 200, 500, 1000, etc., each jump in the base-10 logarithm from one denomination to the next higher is either 0.3010 or 0.3979.