A pan can bake two cakes at the same time, it takes 4 minutes to cook one cake (2 minutes for one side), how many minutes does it take to cook 4 cakes.
一个平底锅每次可以同时烙两张饼，烙熟一张饼需要4分钟(一面需要2分钟)，烙熟4张饼需要多少分钟．
<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<result>8</result>