Roman notation is an additive (and subtractive) system of numerical notation, originally used within the ancient Roman empire that extended far past the Italian peninsula, in which letters are used to denote certain "base" numbers. Arbitrary numbers are then denoted using combinations of these base symbols. Roman numerals were developed about 500 b.c. and were at least partially derived from old Greek alphabet symbols that were not used in the new Latin alphabet. Other symbols were more creatively derived. Some Roman numerals probably came about from counting on fingers. The "I" for one came from holding up one finger, as were the symbols "II" and "III" likewise created from holding up two and three fingers, respectively. The number five was derived from holding up five fingers with the "V" shape made by the thumb and the forefinger. Although not known for sure, the symbol "X" for...