Six percent is written as "0.06" in decimal format. Percent is derived from the Latin term "per centum" that means "by the hundred." It means "one-hundredth part," or 1/100. Six percent is thus six one-hundredth parts, or 6/100.
Percent is used in science and commerce to express numbers on the basis of a proportion per hundred. The usage of percent originated in Ancient Rome when fractions in proportions of one hundred were used. Augustus Caesar levied a tax of 1/100 on goods sold at auctions. During the Middle Ages, denominations of money grew, and computations with a denominator of one hundred became more widespread. In the 15th and 16th centuries computations involving the use of such fractions became common inclusions in arithmetic texts.