Six students in class 2 of the sixth year are going to play table tennis, and every two students have to play a game. How many games are there in total?
六年2班6名同学要进行乒乓球比赛，每两名同学之间要进行一场比赛，一共要进行多少场比赛？
<gadget id="calculator">6 - 1</gadget>
<output>5</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<result>15</result>