There are ten balls numbered 1 to 10 in the box, and Xiaohong takes out nine balls from the box three times. If from the second time onwards, the sum of the numbers of the balls taken out each time is one more than twice the last time, what is the number of the remaining balls?
盒子里放有编号1到10的十个球，小红先后三次从盒子中共取出九个球．如果从第二次起，每次取出的球的编号的和都比上一次的两倍还多一，那么剩下的球的编号为多少．
<result>2</result>