A salt field is 100 meters long and 80 meters wide. How many hectares does 40 such salt fields occupy?
一块盐田长100米，宽80米，40块这样的盐田占地多少公顷．
<gadget id="calculator">40 / 10_000</gadget>
<output>1/250 = around 0.004</output>

<gadget id="calculator">100 * 80 * (1/250)</gadget>
<output>32</output>

<result>32</result>