After combining two cylindrical steel materials with equal base area into a 3-meter-long cylinder, the surface area will be reduced by 0.9 square decimeters. If the steel material weighs 7.8 kilograms per cubic meter, how many kilograms does the assembled steel material weigh?
把两根底面积相等的圆柱形钢材拼成一根长3米的圆柱后，表面积减少0.9平方分米，如果每立方米钢材重7.8千克，拼成后的这根钢材重多少千克？
<gadget id="calculator">0.9 / 2</gadget>
<output>0.45</output>

<gadget id="calculator">0.45 * 30</gadget>
<output>13.5</output>

<gadget id="calculator">13.5 * 7.8</gadget>
<output>105.3</output>

<result>105.3</result>