INFORMATION STORAGE REQUIREMENTS FOR THE CONTENTS OF THE WORLD'S LIBRARIES.

Three calculations of the number of different things stored in the world's libraries yield estimates from 7.5 x 10(7) to 7.7 x 10(8). At 10(5) words per volume, five letters per word, and 12 bits per letter, the information capacity used for storage is between 4.6 x 10(14) and 4.6 x 10(15) bits, and is increasing at about 2 x 10(6) bits per second.