square vegetable field has a perimeter of 3600 meters, how many hectares does this vegetable field have?
一块正方形菜地，周长是3600米，这块菜地有多少公顷？
<gadget id="calculator">3_600 / 4</gadget>
<output>900</output>

<gadget id="calculator">3_600 / 4 / 10_000</gadget>
<output>9/100 = around 0.09</output>

<gadget id="calculator">900 * (9/100)</gadget>
<output>81</output>

<result>81</result>