there are 26 letters in the alphabet, 10 decimal digits in the base 10 number system and several different kinds of punctuation marks, two possibilities for capitalization (on/off) and a few other symbols used in a typical book. A combination of 6 binary bits can take on 64 different possibilities which is about the number needed to create a code equivalent to all the possible characters that make up normal text. the average word in a text contains about 5 characters and with each character requiring 6 bits for its representation, 1 average word of text is equivalent to about 30 bits