Numeral

A numeral is a written expression representing a number. The number five can be written as the decimal numeral $5$, the binary numeral $101_2$, or the Roman numeral V. The expressions differ while the represented integer is the same.

This distinction matters when an algorithm examines numerical digits. A palindromic number, for example, is defined through its representation in a specified radix, rather than through the appearance of an abstract number. The integer five is a palindrome as the one-digit decimal numeral $5$ and as the binary numeral $101_2$, whereas ten is written $10$ in decimal and $1010_2$ in binary, neither of which is a palindrome.