The shopping mall launched the activity of "buy 5 get 1 free" of mineral water. A tourist group of 50 people wants to give each person a bottle of mineral water, how many bottles of water do they need to buy at least?
商场开展矿泉水"买5送1"活动．一个50人的旅游团想每人发一瓶矿泉水，问至少需要买多少瓶水？
<gadget id="calculator">50 - 10</gadget>
<output>40</output>

<gadget id="calculator">40 + 2</gadget>
<output>42</output>

<result>42</result>