A pancake pan can only hold 2 pancakes at most, and it takes 3 minutes to bake one pancake on one side, and at least how many minutes it takes to bake 3 pancakes.
一个烙饼锅最多只能放2张饼，一张饼烙一面需3分钟，烙好3张饼至少要多少分钟．
<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<result>9</result>