You convert a decimal to a fraction by putting the digits to the right of the decimal point over "1" followed by the same number of zeros. (Most folks learn this in 3rd or 4th grade.)
0.66 = 66/100 . . . . . 2 decimals, so the denominator is 100
Then you reduce the fraction by canceling common factors. It helps to know your times tables and divisibility rules. (Or you can have your calculator do it.)
0.66 = 66/100 = 33/50
1.00 = 100/100 = 1
