A conical container filled with water measures 21 cm in depth. Pour all the water into a cylindrical container of the same height as the bottom. What is the depth in cm?
一个盛满水的圆锥形容器，量得水深21cm，将水全部倒入和它等底等高的圆柱形容器里，水深是多少cm．
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">21 * (1/3)</gadget>
<output>7</output>

<result>7</result>