There is a cylinder with a height of 16 cm. If the height increases (1/4), the surface area increases by 12.56 cm2. Find the volume of the original cylinder?
有一个高为16厘米的圆柱体，如果高增加(1/4)，表面积就增加12.56平方厘米，求原来圆柱体的体积？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">16 * (1/4)</gadget>
<output>4</output>

<gadget id="calculator">12.56 / 4</gadget>
<output>3.14</output>

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

<gadget id="calculator">3.14 / 3.14 / 4</gadget>
<output>0.25</output>

<gadget id="calculator">3.14 * 0.25 * 16</gadget>
<output>12.56</output>

<result>12.56</result>