100 kilograms of seawater can produce 2.5 kilograms of salt, and now it is necessary to produce 500 kilograms of salt, how many tons of seawater are needed?
100千克的海水可制盐2.5千克，现要制盐500千克，需要海水多少吨？
<gadget id="calculator">100 / 2.5</gadget>
<output>40</output>

<gadget id="calculator">500 / 1_000</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">40 * (1/2)</gadget>
<output>20</output>

<result>20</result>