In a ratio, the two outer terms are reciprocals of each other, one inner term is 4, and the other inner term is how much.
在一个比例里，两个外项互为倒数，一个内项是4，另一个内项是多少．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>