Use a pan to bake pancakes, you can only put 2 cakes at a time, it takes 4 minutes to bake one side, and both sides have to be baked, how long does it take at least 7 cakes.
用一只平底锅烙饼，每次只能放2张饼，烙一面要4分钟，两面都要烙，烙7张饼至少要用多少钟．
<gadget id="calculator">4 * 2 * 2</gadget>
<output>16</output>

<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<gadget id="calculator">16 + 12</gadget>
<output>28</output>

<result>28</result>