"Six Day" Children's Day, the Cultural Commodities Store is holding promotional activities. A diary is 6 yuan, buy five and get one free. If you buy 30 copies, how much is it cheaper?
"六一"儿童节，文化商品行搞促销活动，一本日记本6元，买五送一，如果买30本，共便宜多少钱？
<gadget id="calculator">6 / 6</gadget>
<output>1</output>

<gadget id="calculator">5 * 1</gadget>
<output>5</output>

<gadget id="calculator">6 - 5</gadget>
<output>1</output>

<gadget id="calculator">1 * 30</gadget>
<output>30</output>

<result>30</result>