Base Two Positional Notation

Positional notation can also be used with a base other than ten. Here is a number written using base two:

When a particular power of the base is not needed, the digit '0' is used for that position. If the base is two, the point  '.'  is called a binary point.

In general, the mark used to separate the fraction from the whole number is called a radix point. In many European nations, the radix point "," is used.