If a square paper with a side length of 1 decimeter is rolled into the largest cylindrical paper tube, what is the lateral area of the cylindrical paper tube in square decimeters? (reserve pi)
把边长1分米的正方形纸卷成一个最大的圆柱形纸筒，那么圆柱纸筒的侧面积是多少平方分米．(保留圆周率π)
<gadget id="calculator">1 * 1</gadget>
<output>1</output>

<result>1</result>