The number A is 100, the number B is (2/5) of the number A, what is the number B?
甲数是100，乙数是甲数的(2/5)，乙数是多少．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">100 * (2/5)</gadget>
<output>40</output>

<result>40</result>