The diameter of a circle is a
quantity which has a unit that is usually rounded to a certain
terminating degree of accuracy (i.e. 1, 2, ..., n decimal places)
Thus the set of rational numbers best describes the diameter of a circle.
A
rational number is a number which can be represented in the form a/b
where a and b are integers. It is usually identified by a terminating or
a recurring decimal number.
