A pan can bake two cakes at a time, both sides need to be baked, each side takes 4 minutes, how many minutes should be used to bake 7 cakes at least.
一个平底锅每次能烙两张饼，两面都要烙，每面4分钟，烙7张饼至少要有用多少分钟．
<gadget id="calculator">2 * 2 * 4</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>