Use a compass to draw a circle with a diameter of 20 mm. What is the distance between the two legs of the compass in mm?
用圆规画一个直径是20毫米的圆，圆规两脚之间的距离应取多少毫米．
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<result>10</result>