If the side length of a square vegetable field is 200 meters, what is its area in hectares?
一块正方形菜地的边长是200米，它的面积是多少公顷．
<gadget id="calculator">200 * 200</gadget>
<output>40_000</output>

<gadget id="calculator">40_000 / 10_000</gadget>
<output>4</output>

<result>4</result>