hi, given N, how can one find all such N digit natural numbers such that the N least significant digits of any integral power of that number is the number itself?

E.g if N =2

then the required numbers are 25 and 76.

because 25^2 = 625 and the 2 least significant digits of 625 are 25 which is the number itself , similary for any integral power of 25 and 76.

Here N can be as large as 500 digits.

Thanks.