The supermarket is promoting yogurt, buy 2 boxes and get 1 box free, 12 students want to drink one box each, at least how many boxes to buy.
超市搞酸奶促销，买2盒送1盒，12名学生要每人喝一盒，至少买多少盒．
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<gadget id="calculator">12 / 3</gadget>
<output>4</output>

<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<result>8</result>