80/100 as a Decimal 0.8 80/100 = 0.8 = 80% Copy 80/100 = 0.8 = 80%. Simplified: 4/5. Formula Used80 ÷ 100 = 0.8 Frequently Asked Questions What is 80/100 as a decimal?0.8.What is 80/100 as a percentage?80%.