The advertising company pastes a square poster on the side of a cylindrical light box with a bottom circumference of 8 decimeters, just enough to fill it up. What is the side area of this cylindrical light box in square decimeters?
广告公司将一张正方形海报贴在一个底面周长为8分米的圆柱形灯箱的侧面，刚好贴满，这个圆柱形灯箱的侧面积是多少平方分米．
<gadget id="calculator">8 * 8</gadget>
<output>64</output>

<result>64</result>