To prepare a pesticide, the ratio of liquid medicine to water is 1:1000, now there is 50kg of water, how many grams of pesticide should be added.
要配制一种农药，药液与水的比是1：1000，现在有水50千克，需要加入农药多少克．
<gadget id="calculator">1 / 1_000</gadget>
<output>1/1_000 = around 0.001</output>

<gadget id="calculator">50 * (1/1_000) * 1_000</gadget>
<output>50</output>

<result>50</result>