Total no of words = (9*8*7*6*5*4*3*2*1)/(2*1*2*1) = 90720
In denominator 2*1 and 2*1 used due to revision of D & E twice
90720*7/9 + 10080*3/8 + 1260*2*1/7 + 360*2*3/6 + 120*2/5 + 24*2/4 + 6*1/3 + 2*0/2 + 1
= 70560 + 3780 + 360 + 360 + 48 + 12 + 2 + 0 + 1 = 75123