Decimal the Roman numerals did, an intermediate base of 5. Notably, the polymath Archimedes (ca. 287–212 BC) invented a decimal positional system in his Sand Reckoner which was based on 10 and later led the German mathematician Carl Friedrich Gauss to lament what heights science would have already reached in his days if Archimedes had fully realized the potential of his ingenious discovery. The Hittites hieroglyphs (since 15th century BC), just like the Egyptian and early numerals in Greece, was strictly decimal. Some non-mathematical ancient texts like the Vedas dating back to 1900–1700 BCE make use of decimals and mathematical decimal
Repeating decimal 9. Knowing just that, a general repeating decimal can be expressed as a fraction without having to solve an equation. For example, one could reason: It is possible to get a general formula expressing a repeating decimal with an "n" digit period (repetend length), beginning right after the decimal point, as a fraction: More explicitly one gets the following cases. If the repeating decimal is between 0 and 1, and the repeating block is "n" digits long, first occurring right after the decimal point, then the fraction (not necessarily reduced) will be the integer number represented by the "n"-digit block