A rectangular piece of land is 400 meters long and 300 meters wide. How many hectares will the area increase if it is made into the largest square?
一块长方形土地，长400米，宽300米．若把它变成最大的正方形，面积增加多少公顷？
<gadget id="calculator">400 * 400</gadget>
<output>160_000</output>

<gadget id="calculator">400 * 300</gadget>
<output>120_000</output>

<gadget id="calculator">160_000 - 120_000</gadget>
<output>40_000</output>

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

<result>4</result>