In a cylindrical glass tank with a half-diameter of 20 cm at the bottom, a cylindrical steel material with a half-diameter of 10 cm is immersed in the water in the tank. When the steel material is taken out of the tank, the water level drops by 1 cm. Find the value of the steel material how high?
在一个底面半经是20厘米的圆柱形玻璃缸内，有一段半经为10厘米的圆柱形钢材浸没在该缸内水中，当钢材从缸内取出时，水面下降了1厘米，求钢材有多高？
<gadget id="calculator">20 ** 2</gadget>
<output>400</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">3.14 * 100</gadget>
<output>314</output>

<gadget id="calculator">1 / 314</gadget>
<output>1/314 = around 0.003185</output>

<gadget id="calculator">3.14 * 400 * (1/314)</gadget>
<output>4</output>

<result>4</result>