Xiaoming’s family wants to design a kitchen chimney pipe. The cross-section is a square with a circumference of 24 decimeters. The chimney is 3 meters long. What is the minimum iron sheet required to make this chimney pipe?
小明家要设计一个厨房烟囱管，横截面是一个周长为24分米的正方形，这个烟囱长3米，制成这个烟囱管至少需要多大的铁皮？
<gadget id="calculator">3 * 10</gadget>
<output>30</output>

<gadget id="calculator">24 * 30</gadget>
<output>720</output>

<result>720</result>