If two identical cylinders have a base diameter of 6 cm and a length of 2.5 decimeters, when the two cylinders are joined together, how much is the surface area reduced from the sum of the surface areas of the original two cylinders?
两个同样的圆柱，它们的底面直径为6厘米，长为2.5分米，把这两个圆柱连接在一起，表面积比原来两个圆柱的表面积的和减少了多少？
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<gadget id="calculator">3.14 * 9 * 2</gadget>
<output>56.52</output>

<result>56.52</result>