90/100 as a Decimal 0.9 90/100 = 0.9 = 90% Copy 90/100 = 0.9 = 90%. Simplified: 9/10. Formula Used90 ÷ 100 = 0.9 Frequently Asked Questions What is 90/100 as a decimal?0.9.What is 90/100 as a percentage?90%.