Prepare a liquid medicine and water at a ratio of 1:2500 to make a liquid medicine. How many kilograms of this liquid medicine should be placed in 1000 kilograms of water.
把一种药液与水按1：2500配制成药水，在1000千克水中要放这种药液多少千克．
<gadget id="calculator">1 / 2_500</gadget>
<output>1/2_500 = around 0.0004</output>

<gadget id="calculator">(1/2_500) * 1_000</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>