A square piece of paper with a side length of 5 decimeters is rolled into a cylinder, what is the lateral area of the cylinder in square decimeters?
将一个边长为5分米的正方形纸片卷成圆柱筒，这个圆柱的侧面积是多少平方分米．
<gadget id="calculator">5 * 5</gadget>
<output>25</output>

<result>25</result>