10/20 as a Decimal 0.5 10/20 = 0.5 = 50% Copy 10/20 = 0.5 = 50%. Simplified: 1/2. Formula Used10 ÷ 20 = 0.5 Frequently Asked Questions What is 10/20 as a decimal?0.5.What is 10/20 as a percentage?50%.