To use a compass to draw a circle with a diameter of 9 cm on paper, what is the distance between the two feet of the compass in cm?
要用圆规在纸上画一个直径为9厘米的圆，圆规两脚间距离应取多少厘米．
<gadget id="calculator">9 / 2</gadget>
<output>9/2 = around 4.5</output>

<result>9/2 = around 4.5</result>