Base Two Positional Notation

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

1
 
0
 
0
 
 . 
 
1
 
0
 
1


1×22+
 
0×21+
 
0×20+
 
 .
 
1×2-1+
 
0×2-2+
 
1×2-3

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.