40 students are going on an autumn tour, each of them needs a bottle of water, and each bottle is 2 yuan. The store holds a "buy 4 get 1 free" event, so how much they need to pay at least.
40名学生去秋游，他们每人需要一瓶水，每瓶2元．商店举行"买4送1"活动，那么他们至少需要付多少元钱．
<gadget id="calculator">2 * 4</gadget>
<output>8</output>

<gadget id="calculator">40 / 5</gadget>
<output>8</output>

<gadget id="calculator">8 * 8</gadget>
<output>64</output>

<result>64</result>