-- There are an infinite number of different numbers between 2.65 and 2.66 . To create one, just write ' 2.65 ' and add any quantity of any digits you want after the ' 5 '.
-- If you want the number that's exactly in the middle between them, then that's just the <em><u>average</u></em> of the two numbers.
The average of any two numbers is (1/2) x (the sum of the numbers).