0.6 is equal to itself, so all instances of it can be grouped together in the list. Any positive decimal number is less than that same number with additional digits appended, so 0.6 < 0.65.
In this list of least-to-greatest, the values 0.6 will precede the value 0.65:
, where 
is circumference and tex]d[/tex] is the diameter. They are related by a constant 
(pi).