There are 3 guests in the house, one walks every 5 minutes, and all the guests are gone, how much will it take
家中有3位客人，每5分钟走一位，所有客人都走完了，则需要多少
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">2 * 5</gadget>
<output>10</output>

<result>10</result>