Teacher Li of Yannan Elementary School bought back 18 boxes of chalk, 12 boxes per box, and 3 yuan per box. How much did Yannan Primary School spend on chalk?
雁南小学李老师买回18箱粉笔，每箱12盒，每盒3元．雁南小学买粉笔共花了多少钱？
<gadget id="calculator">12 * 3 * 18</gadget>
<output>648</output>

<result>648</result>