In 8*7*6*5*4*3 = 20160 different ways. 1-st person can take any of 8 chairs. - 8 possibilities. 2-nd person can take any of remaining 7 chairs. - 7 possibilities. 3-rd person can take any of remaining 6 chairs. - 6 possibilities. . . . . And so on . . . . 6-th person can take any of remaining 3 chairs. - 3 possibilities. Thus there are 8*7*6*5*4*3 = 20160 different ways.