The two inner terms of the ratio are reciprocals of each other, then one of its outer terms is 2, then what is the other outer term.
比例的两个内项互为倒数，那么它的其中一个外项为2，则另一个外项为多少．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>