6 classmates take pictures, and every 2 of them need a group photo, how many photos should be taken in total.
6个同学照相，每2个人都要一张合影，一共要照多少张相．
<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">6 * (5/2)</gadget>
<output>15</output>

<result>15</result>