666 (number) on 1/149 in base 10 has a magic total of 666. The prime factorization of 666 is 2 • 3 • 37. Also, 666 is the sum of squares of first seven primes: formula_2 The Roman numeral for 666, DCLXVI, has exactly one occurrence of all symbols whose value is less than 1000 in decreasing order (D = 500, C = 100, L = 50, X = 10, V = 5, I = 1). In the Textus Receptus manuscripts of the New Testament, the Book of Revelation () cryptically asserts 666 to be "man's number" or "the number of a
Roman numerals use of Roman numerals persists in some minor applications to this day. The original pattern for Roman numerals used the symbols I, V, and X (1, 5, and 10) as simple tally marks. Each marker for 1 () added a unit value up to 5 (), and was then added to () to make the numbers from 6 to 9: The numerals for 4 () and 9 () proved problematic (among other things, they are easily confused with and , especially at a quick glance), and are generally replaced with (one less than 5) and (one less than 10). This