A cylindrical grain tun with a bottom diameter of 10 meters and a height of 4 meters is filled with half of the wheat. How many cubic meters of wheat are packed?
一个圆柱形的粮屯，底面直径是10米，高4米，粮屯内装了一半的小麦．装的小麦有多少立方米？
<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">3.14 * 25 * 2</gadget>
<output>157</output>

<result>157</result>