A rectangular test field has 4.2 hectares, its length is 420 meters, what is its width in meters?
一块长方形试验田有4.2公顷，它的长是420米，它的宽是多少米．
<gadget id="calculator">4.2 * 10_000</gadget>
<output>42_000</output>

<gadget id="calculator">42_000 / 420</gadget>
<output>100</output>

<result>100</result>