character if you use entropy encoding off individual characters of your two to the seven this is 128 or simply 128 characters you use entropy encoding you know I need 4.5 bits per character that's of course the ball it is if you look at entropy but you can't perfectly achieve that because you have to brown to a finite number of bits so - code which is optimal achieves four point seven now if you look at the entropy of groups of eight symbols and then look at the average entropy per character you can line up 2.4 now some