posted by molly on .
How many possible arrangments are there of the letters A,B,C,D,E,F in which E and F are not next to eachother?
with no restriction there would be 6! or 720 ways
the no of ways in which the E and F are together = 2(5!) ways or 240
so the number of ways the E and F are apart are 720 - 240 or