Use a pan to fry fish, only 2 fish can be fried at a time, and it takes 2 minutes to fry one fish (1 minute for each side). If you want to fry 7 fish, how many minutes will it take at least.
用一个平底锅煎鱼，每次只能煎2条，煎一条鱼需要2分钟(正反面各需1分钟)，如果要煎7条鱼，最少需要多少分钟．
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">1 * 3</gadget>
<output>3</output>

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

<result>7</result>