Roman Numerals / 15

15 in Roman Numerals

XV

15 = X (10), V (5). That's XV, purely additive. 15 splits into 1 ten (X), 5 (V), together forming XV. One below 15 is XIV (14); one above is XVI (16). At 2 symbols, XV is compact for 15. 15: 2 Arabic digits, 2 Roman symbols, for 15. In binary, 15 is 1111, 4 bits long for 15.