any numeral system defines the value of all numbers that contain more than one digit, most often by addition of the value for adjacent digits. the hindu–arabic numeral system includes positional notation to determine the value for any numeral. in this type of system, the increase in value for an additional digit includes one or more multiplications with the radix value and the result is added to the value of an adjacent digit. with arabic numerals, the radix value of ten produces a value of twenty-one (equal to ) for the numeral "21". an additional multiplication with the radix value occurs for each additional digit, so the numeral "201" represents a value of two-hundred-and-one (equal to ).