A cylindrical cement pipe has an outer diameter of 2.5 meters, an inner diameter of 2 meters, and a height of 2 meters. How many cubic meters of material are needed to make this cement pipe?
一个圆柱形水泥管的外圆直径是2.5米，内圆直径是2米，高是2米，做这个水泥管需要多少立方米的材料？
<gadget id="calculator">2.5 / 2</gadget>
<output>1.25</output>

<gadget id="calculator">1.25 ** 2</gadget>
<output>1.5625</output>

<gadget id="calculator">3.14 * 1.5625</gadget>
<output>4.90625</output>

<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">1 ** 2</gadget>
<output>1</output>

<gadget id="calculator">3.14 * 1</gadget>
<output>3.14</output>

<gadget id="calculator">4.90625 - 3.14</gadget>
<output>1.76625</output>

<gadget id="calculator">1.76625 * 2</gadget>
<output>3.5325</output>

<result>3.5325</result>