Three identical small cylinders are all 7 cm high. If they are combined into a large cylinder, the surface area is reduced by 100.48 cm2. What is the volume of the combined large cylinder in cubic centimeters?
三个相同的小圆柱，高都是7厘米，将它们合并成一个大的圆柱，表面积减少了100.48平方厘米，那么合并后的大圆柱体积是多少立方厘米？
<gadget id="calculator">100.48 / 4</gadget>
<output>25.12</output>

<gadget id="calculator">7 * 3</gadget>
<output>21</output>

<gadget id="calculator">25.12 * 21</gadget>
<output>527.52</output>

<result>527.52</result>