There are 7 players participating in the summer youth chess competition. There is a match between two players, and the player with the most points wins. How many rounds will there be in this game?
暑假青少年国际象棋比赛，有7名选手参加．每两人比赛一场，积分高者胜．这次比赛共要赛多少场？
<gadget id="calculator">7 - 1</gadget>
<output>6</output>

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

<gadget id="calculator">7 * 3</gadget>
<output>21</output>

<result>21</result>