There are 10 chess players participating in a Go match in turn, and each player has to play one game with other players, how many games are needed in total.
有10名棋手参加依次围棋比赛，每人都要和其他选手赛一场，共需要赛多少场．
<gadget id="calculator">9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1</gadget>
<output>45</output>

<result>45</result>