To prepare a medicine, the mass ratio of medicine to water is 1:500, how many kilograms of medicine can be prepared from 2000 kilograms of existing water?
配制一种药水，药的质量与水的质量比是1：500，现有水2000千克可以配制成药水多少千克？
<gadget id="calculator">1 / 500</gadget>
<output>1/500 = around 0.002</output>

<gadget id="calculator">2_000 * (1/500)</gadget>
<output>4</output>

<gadget id="calculator">4 + 2_000</gadget>
<output>2_004</output>

<result>2_004</result>