3 male students play ball with 3 female students. If each male student has to play with each female student once, how many games are needed in total?
3个男同学与3个女同学进行打球比赛，如果每个男同学都要与每个女同学比赛1次，一共需要比赛多少次．
<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<result>9</result>