After a cylinder with a diameter of 8 cm is cut longitudinally along the height, the surface area increases by 200 cm**2. What is the original volume of the cylinder?
把一个直径是8厘米的圆柱沿高纵向切开以后，表面积增加了200厘米**2，原来这个圆柱的体积是多少？
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">200 / 2 / 8</gadget>
<output>25/2 = around 12.5</output>

<gadget id="calculator">3.14 * 16 * (25/2)</gadget>
<output>628</output>

<result>628</result>