To cut two circles with a radius of 3 cm on a rectangular piece of paper, what is the minimum area of the piece of paper?
要在一张长方形纸片上剪2个半径是3厘米的圆，这张纸的面积至少是多少
<gadget id="calculator">3 * 2 * 2</gadget>
<output>12</output>

<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">12 * 6</gadget>
<output>72</output>

<result>72</result>