If the perimeter of a cube is 20dm, what is its volume?
一个正方体的底面周长是20dm，它的体积是多少．
<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<gadget id="calculator">5 * 5 * 5</gadget>
<output>125</output>

<result>125</result>