Roman Numerals / 20

20 in Roman Numerals

XX

20 = XX (10). That's XX, purely additive. 20 splits into 2 tens (XX), together forming XX. One below 20 is XIX (19); one above is XXI (21). At 2 symbols, XX is compact for 20. 20: 2 Arabic digits, 2 Roman symbols, for 20. In binary, 20 is 10100, 5 bits long for 20.