It costs 3 yuan per square meter to advertise on a rectangular wall with a length of 18 meters and a width of 12 meters. How much does it cost to make this wall advertisement?
在一面长18米，宽12米的长方形墙面上做广告，每平方米需要3元钱，做这个墙体广告一共需要多少钱？
<gadget id="calculator">18 * 12 * 3</gadget>
<output>648</output>

<result>648</result>