Mineral water weighs 21 kilograms per barrel and sells for 12 yuan. How much does it cost for the school to buy 23 barrels of such mineral water?
矿泉水每桶重21千克，售价12元．学校买23桶这样的矿泉水，需要多少元．
<gadget id="calculator">12 * 23</gadget>
<output>276</output>

<result>276</result>