In a ratio, the two inner terms are reciprocals of each other, one of the outer terms is 4, and the other is how many.
在一个比例中，两个内项互为倒数，其中一个外项是4，另一个外项是多少．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

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