Xiaohong uses a pan to make pancakes, and can only put 2 cakes at a time. It takes 2 minutes to bake a cake (1 minute for the front and back). In order to save time, how many minutes does it take for Xiaohong to bake 7 cakes at least.
小红用平底锅烙饼，每次只能放2张饼．烙一张饼需要2分钟(正、反面各需1分钟)．为了节约时间，小红要烙7张饼最少需要多少分钟．
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">4 + 3</gadget>
<output>7</output>

<result>7</result>