Let's take the steps to go from a fraction to a decimal and then finally a percentage.
First, divide the numerator (the top portion of the fraction) by the denominator (the bottom portion of the fraction).

Next, multiply the quotient by 100 and tack a percent sign.
0.666... * 100 = 66.666...%
Decimal portion of the percent needs to be converted to the equivalent fraction.
0.666... = 2/3
Now the final answer is 66 2/3%