There is a ratio, the two inner terms are reciprocals of each other, one outer term is 1.8, and the other outer term is how much.
有一个比例，两个内项互为倒数，一个外项是1.8，另一个外项是多少．
<gadget id="calculator">1 / 1.8</gadget>
<output>0.555556</output>

<result>0.555556</result>