In a ratio, the two internal terms are reciprocals of each other, and one of the external terms is 2.5, so what is the other external term
在一比例中，两个内项互为倒数，其中一个外向为2.5，那么，另一个外项是多少
<gadget id="calculator">1 / 2.5</gadget>
<output>0.4</output>

<result>0.4</result>