30 students want to buy a bottle of soda each, and the shopping mall has a promotion. Buy 5 bottles and get 1 free. You only need to pay for the bottle.
30名同学要每人买一瓶汽水，商场促销，买5瓶送1瓶，只需要付多少瓶的钱就够了．
<gadget id="calculator">5 + 1</gadget>
<output>6</output>

<gadget id="calculator">30 / 6</gadget>
<output>5</output>

<gadget id="calculator">5 * 5</gadget>
<output>25</output>

<result>25</result>