The school dance classroom needs to install a mirror with a length of 12 meters and a width of 3 meters. The price of this mirror is 24 yuan per square meter. How much does it cost to buy this mirror?
学校舞蹈教室要安装一面长12米，宽3米的镜子，这种镜子的价格是每平方米24元，买这面镜子要花多少钱？
<gadget id="calculator">12 * 3 * 24</gadget>
<output>864</output>

<result>864</result>