In proportion, the product of two outer terms is the smallest prime number, if one inner term is 4, what is the other inner term.
在比例中，两外项之积为最小质数，若一内项为4，另一内项是多少．
<gadget id="calculator">2 / 4</gadget>
<output>1/2 = around 0.5</output>

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