All common fractions can be converted to decimal fractions by dividing the numerator by the denominator. For example:

• ½ = 0.5

Ancient mathematical records—Hindu-Arabic, Greek, Egyptian, and Babylonian—show many different methods for noting fractions. However, Islamic scholars were the first to convert fractions to decimal analogues. During the Middle Ages, scholars used the Babylonian system of sexagesimal (base 60) fractions for computation, particularly when calculating square roots and cube roots. In the fifteenth century, the astronomer al-Kashi invented a method for converting sexagesimal fractions to decimal fractions. Al-Kashi also discovered a way to approximate the value of 2 in both sexagesimal and decimal fractions.

Despite al-Kashi's discovery, the use of decimal fractions evolved very slowly. Johannes Regiomontanus (1436-1476) compiled tables of sines and cotangents that were very close to decimal fractions. In 1585, Simon Stevin (1548-1620) was the first to offer conceptual details of decimal fractions and...