To make a cube box without a lid, with a side length of 7 decimeters, what is the minimum area of the iron sheet?
制作一个正方体无盖盒，棱长为7分米，至少需要多大面积的铁皮？
<gadget id="calculator">7 * 7 * 5</gadget>
<output>245</output>

<result>245</result>