Roman Numerals / 13

13 in Roman Numerals

XIII

13 = X (10), III (1). That's XIII, purely additive. 13 splits into 1 ten (X), 3 (III), together forming XIII. One below 13 is XII (12); one above is XIV (14). XIII hits the 3-repeat cap with III, for 13. 13: 2 Arabic digits, 4 Roman symbols, for 13. In binary, 13 is 1101, 4 bits long for 13.