Let A={x1,x2,x3,x4,x5,x6},B={y1,y2,y3,y4,y5,y6}.Then the number of one-one mappings from A to B such that f(x_i ) not equal to y_i i=1,2,3,4,5,6 is

n-1 ways...

thats the number of combinations possible... please verify.......as we take 2 elements one arrangement possible, 3 elements 2 arrangements possible

 

For 6 terms....its 6 factorial ((1/2!)-(1/3!)+.....

. Thus the answer 265...

Therefore there is 265 ways in which two sets can be mapped

both of the above comments are by me only.