science laboratory is 12 meters long, 10 meters wide, and 50 decimeters high. Now it is necessary to paint the ceiling and four walls of the laboratory, excluding doors, windows and blackboards, the area is 30 square meters, and an average of 0.2 kilograms of lime is used per square meter. How many kilograms of lime are needed in total?
一个科学实验室长12米，宽10米，高50分米．现在要粉刷实验室的天花板和四面墙壁，除去门窗和黑板的面积30平方米，平均每平方米用去石灰0.2千克，一共需要石灰多少千克？
<gadget id="calculator">12 * 10</gadget>
<output>120</output>

<gadget id="calculator">50 / 10</gadget>
<output>5</output>

<gadget id="calculator">12 * 5 * 2</gadget>
<output>120</output>

<gadget id="calculator">10 * 5 * 2</gadget>
<output>100</output>

<gadget id="calculator">100 - 30</gadget>
<output>70</output>

<gadget id="calculator">120 + 120 + 70</gadget>
<output>310</output>

<gadget id="calculator">310 * 0.2</gadget>
<output>62</output>

<result>62</result>