Each bottle of shampoo is 18 yuan, buy 4 bottles and get one bottle free, mother buys 10 bottles at a time, how much is the share.
每瓶洗发水18元，买4瓶送一瓶，妈妈一次买10瓶，共用多少元．
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">10 / 5</gadget>
<output>2</output>

<gadget id="calculator">2 * 4 * 18</gadget>
<output>144</output>

<result>144</result>