Etruscan numerals

The Roman numeral system is a cousin of Etruscan numerals.

The Etruscan numerals were used by the ancient Etruscans.

Roman numerals are a numeral system originating in ancient Rome, adapted from Etruscan numerals.

The Etruscan numerals are known although debate lingers about which numeral means "four" and which "six" (huθ or śa).

Also, the principles and architecture rules of their decimal numerals system are likewise at the origin of the Roman one, actually a simplified version (see: Etruscan numerals).