What number in binary can only be represented as an approximation?

Question

In decimal (base 10), 1/3 can only be approximated to 0.33333 repeating.

What number is the equivalent in binary that can only be represented as an app

Answer 1

In python 2.4:

>>> 1.0 / 5.0
0.20000000000000001

That indicates that base 2 has a hard time representing it exactly.