There are 5 kinds of fruits, and every 2 kinds of fruits make a platter, how many kinds can be combined.
有5种水果，每2种水果做一个拼盘，可以拼多少种．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">4 * (5/2)</gadget>
<output>10</output>

<result>10</result>