围绕着山顶有10个圆形排列的洞，狐狸要吃兔子，兔子说：“可以，但必须找到我，我就藏身于这十个洞中，你先到１号洞找，第二次隔１个洞（即3号洞）找，第三次隔２个洞（即6号洞）找，以后如此类推，次数不限。”但狐狸从早到晚进进出出了1000次，仍没有找到兔子。问兔子究竟藏在哪个洞里 ?

-Peak around the circular array of 10 holes, the fox eat the rabbit, the rabbit said: " Yes, but you find me, I' ll hide in these ten holes, hole No. 1 you are looking for first, second compartment 1 hole (ie, hole No. 3) looking for a third every 2 holes (ie hole No. 6) to find, since so on unlimited number of times. " But the fox morning till night and out of the 1000, still have not found rabbit. Asked the rabbit hole in which is hiding?