The students go to buy drinks, the supermarket implements a "buy four get one free" promotion, 45 students each get a bottle, how many bottles of drinks do they need to buy at least.
同学们去买饮料，超市实行"买四送一"的优惠活动，45个同学每人一瓶瓶，最少需买多少瓶饮料．
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">45 / 5</gadget>
<output>9</output>

<gadget id="calculator">45 - 9</gadget>
<output>36</output>

<result>36</result>