circular steel bar with a length of 40 cm is divided into two sections of the same length, and the surface area increases by 30 cm2. What is the volume of this circular steel bar in cubic centimeters?
一根长40厘米的圆形钢条，分成一样长的两段，表面积增加30平方厘米，原来这根圆形钢条的体积是多少立方厘米？
<gadget id="calculator">30 / 2</gadget>
<output>15</output>

<gadget id="calculator">15 * 40</gadget>
<output>600</output>

<result>600</result>