He made contributions to Narcissistic numbers and Fibonacci series.

The sequence of "base 10" narcissistic numbers starts:

In the second grade, he attempted to find a 70-digit narcissistic number in base 12 - Eppes has described himself as "quixotic" in elementary school.

The term "narcissistic number" is sometimes used in a wider sense to mean a number that is equal to any mathematical manipulation of its own digits.

Unlike narcissistic numbers, no upper bound can be determined for the size of PDIs in a given base, and it is not currently known whether or not the number of PDIs for an arbitrary base is finite or infinite.

He made contributions to Narcissistic numbers and Fibonacci series.

The sequence of "base 10" narcissistic numbers starts:

In the second grade, he attempted to find a 70-digit narcissistic number in base 12 - Eppes has described himself as "quixotic" in elementary school.

The term "narcissistic number" is sometimes used in a wider sense to mean a number that is equal to any mathematical manipulation of its own digits.

Unlike narcissistic numbers, no upper bound can be determined for the size of PDIs in a given base, and it is not currently known whether or not the number of PDIs for an arbitrary base is finite or infinite.