There is a cylindrical paper barrel with a length of 1.2 meters. If the length is increased by 0.4 meters, the surface area will increase by 2.512 square meters. What is the original volume of the paper barrel in cubic meters?
有一根长1.2米的圆柱形纸桶，若长增加0.4米，则表面积就增加2.512平方米，这个纸筒原来的体积是多少立方米？
<gadget id="calculator">2.512 / 0.4 / 3.14 / 2</gadget>
<output>1</output>

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

<gadget id="calculator">3.14 * 1 * 1.2</gadget>
<output>3.768</output>

<result>3.768</result>