Cut 4 round iron sheets with a radius of 2 cm, and at least a rectangular iron sheet with an area of square centimeters.
剪半径是2厘米的圆形铁片4个，至少要准备面积是多少平方厘米的长方形铁皮．
<gadget id="calculator">2 * 8 * 2 * 2</gadget>
<output>64</output>

<result>64</result>