66/100 as a Decimal 0.66 66/100 = 0.66 = 66% Copy 66/100 = 0.66 = 66%. Simplified: 33/50. Formula Used66 ÷ 100 = 0.66 Frequently Asked Questions What is 66/100 as a decimal?0.66.What is 66/100 as a percentage?66%.