Repdigits
A repdigit is a natural number composed of repeating instances of the same digit. For example, 11, 222, 3333, and 777777 are repdigits. The term repdigit is a portmanteau of "repeat" and "digit".
Repdigits can be represented mathematically. A repdigit consisting of the digit 'd' repeated 'n' times can be
Repdigits have interesting properties in number theory. For example, any repdigit with an even number of digits
The concept of repdigits is also explored in recreational mathematics. Identifying repdigits or exploring their divisibility