The average of the three numbers is 63, and the ratio of the three numbers is 1:3:5. What is the smallest number among the three numbers?
三个数的平均数是63，三个数的比是1：3：5请问这三个数中的最小数是多少．
<gadget id="calculator">63 * 3</gadget>
<output>189</output>

<gadget id="calculator">1 + 3 + 5</gadget>
<output>9</output>

<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">189 * (1/9)</gadget>
<output>21</output>

<result>21</result>