Each sapling is 12 yuan, buy 5 and get 1 free, buy 5 at a time, how much is each sapling cheaper.
每棵树苗12元，买5棵送1棵，一次买5棵，每棵便宜多少元．
<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">12 * (5/6)</gadget>
<output>10</output>

<gadget id="calculator">12 - 10</gadget>
<output>2</output>

<result>2</result>