Step 1: Start with the fraction 66/80.

Step 2: To convert a fraction into a percentage, divide the numerator by the denominator.

66 ÷ 80 = 0.825

Step 3: Multiply the result by 100 to get the percentage.

0.825 × 100 = 82.5%

Final Answer: 66/80 as a percentage is 82.5%.