<P> Herbert S. Zim , in his classic introductory cryptography text `` Codes and Secret Writing '' , gives the English letter frequency sequence as `` ETAON RISHD LFCMU GYPWB VKJXQ Z '' , the most common letter pairs as `` TH HE AN RE ER IN ON AT ND ST ES EN OF TE ED OR TI HI AS TO '' , and the most common doubled letters as `` LL EE SS OO TT FF RR NN PP CC '' . </P>
<P> Herbert S. Zim , in his classic introductory cryptography text `` Codes and Secret Writing '' , gives the English letter frequency sequence as `` ETAON RISHD LFCMU GYPWB VKJXQ Z '' , the most common letter pairs as `` TH HE AN RE ER IN ON AT ND ST ES EN OF TE ED OR TI HI AS TO '' , and the most common doubled letters as `` LL EE SS OO TT FF RR NN PP CC '' . </P>
letters of the alphabet in order of usage
letters of the alphabet in order of usage
ETAON RISHD LFCMU GYPWB VKJXQ Z
ETAON RISHD LFCMU GYPWB VKJXQ Z