A square orchard is surrounded by fences, and the shared fence is 1600 meters. How many hectares does the orchard cover?
一个正方形果园的四周用篱笆围成，共用篱笆1600米，这个果园的占地面积是多少公顷？
<gadget id="calculator">1_600 / 4</gadget>
<output>400</output>

<gadget id="calculator">1_600 / 4 / 10_000</gadget>
<output>1/25 = around 0.04</output>

<gadget id="calculator">400 * (1/25)</gadget>
<output>16</output>

<result>16</result>