If a rectangular orchard with a length of 200 meters and a width of 50 meters is doubled, how many hectares will the area of the orchard increase?
一个长200米、宽50米的长方形果园，如果长与宽都扩大为原来的2倍，那么果园的面积增加多少公顷？
<gadget id="calculator">50 / 10_000</gadget>
<output>1/200 = around 0.005</output>

<gadget id="calculator">200 * (1/200) * 4</gadget>
<output>4</output>

<gadget id="calculator">200 * (1/200)</gadget>
<output>1</output>

<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<result>3</result>