When two factors (except 0) are multiplied, one factor is multiplied by 3 times, and the other factor is multiplied by 5 times.
两个因数(0除外)相乘，一个因数扩大3倍，另一个因数扩大5倍，积就多少．
<gadget id="calculator">3 * 5</gadget>
<output>15</output>

<result>15</result>