The Babylonians used extensive libraries of clay tablets, with many kinds of number facts recorded on them, to solve problems. Babylonian scribes made wedge-shaped symbols for numbers on soft clay tablets. The tablet became a permanent record after it was allowed to dry and harden. Clay tablets were used instead of the papyrus scrolls of Egypt, and they were, in fact, made from the same basic material as that used in the construction of homes and public buildings. The several hundred tablets discovered that relate to mathematics are frequently"text tablets" that state problems as well as their step-by-step solutions, or"problem tablets,' that contain long lists of problems to be solved. The libraries, or"tablet houses" where the tablets were catalogued and stored, also served as the training place for scribes.