Roman Numerals / 18

18 in Roman Numerals

XVIII

18 = X (10), V (5), III (1). That's XVIII, purely additive. 18 splits into 1 ten (X), 8 (VIII), together forming XVIII. One below 18 is XVII (17); one above is XIX (19). XVIII hits the 3-repeat cap with III, for 18. 18: 2 Arabic digits, 5 Roman symbols, for 18. In binary, 18 is 10010, 5 bits long for 18.