A tree is 12 yuan. If you buy 5 trees and get 1 free, how much is each tree cheaper?
一棵树12元，如果买5棵送1棵的话，那么每棵便宜了多少元．
<gadget id="calculator">5 + 1</gadget>
<output>6</output>

<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>