A square grassland has a circumference of 1600 meters, how many hectares does this grassland have?
一块正方形草地，周长1600米，这块草地有多少公顷？
<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>