The base of a cuboid is a square, and the sides are expanded to form a square with a side length of 20 cm. What is the volume of this cuboid in cubic centimeters?
一个长方体的底面是一个正方形，侧面展开后是一个边长是20厘米的正方形，这个长方体的体积是多少立方厘米．
<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<gadget id="calculator">5 * 5 * 20</gadget>
<output>500</output>

<result>500</result>