45 students went to the garden, and each of them had to drink a bottle of mineral water. The store buys 4 bottles and gets 1 free, so they only need to buy as many bottles of mineral water as they need.
45名学生去游园，他们每人要喝1瓶矿泉水．商店买4瓶送1瓶，那么他们只需要买多少瓶矿泉水就正好够．
<gadget id="calculator">9 * 4</gadget>
<output>36</output>

<result>36</result>