A cylindrical steel is 12 meters long. If it is cut into 3 equal sections (the section is parallel to the bottom), its surface area will increase by 18 square decimeters. If each cubic decimeter of steel weighs 7.8 kilograms, how many kilograms does this piece of steel originally weigh?
一根圆柱形钢材长12米，如果将它截成相等的3段(截面与底面平行)，它的表面积就增加了18平方分米．如果每立方分米钢重7.8千克，这根钢材原来重多少千克？
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">18 / 4</gadget>
<output>9/2 = around 4.5</output>

<gadget id="calculator">12 * 10</gadget>
<output>120</output>

<gadget id="calculator">(9/2) * 120 * 7.8</gadget>
<output>4_212</output>

<result>4_212</result>