A square iron sheet with a side length of 20 cm, cut off the largest circle to make the bottom of the barrel, what is the utilization rate of this iron sheet?
一个边长是20厘米的正方形铁片，剪去一个最大的圆做桶底，求这张铁片的利用率？
<gadget id="calculator">3.14 * 100</gadget>
<output>314</output>

<gadget id="calculator">20 * 20</gadget>
<output>400</output>

<gadget id="calculator">314 / 400</gadget>
<output>157/200 = around 0.785</output>

<gadget id="calculator">100 / 100</gadget>
<output>1</output>

<gadget id="calculator">(157/200) * 1</gadget>
<output>157/200 = around 0.785</output>

<result>157/200 = around 0.785</result>