Divide it. Say you have 20 and want to know what percent of 100 20 is. 20/100= .20 (20 percent) (read percent as parts of 100) You have 100 and you want to know what 40 percent of 100 is? 100 x .40 = 40

If the number =x then .2x=answer. --> in words: (20%)*(number)=20% of the number. But percent is (x/y)*100 so you have to divide by 100 to get the number you multiply by; that's why the 20% is 0.2 in the equation.