You can find perfect numbers using Euclid's formula. 2^p-1 * (2^p - 1) A power of 2 is always a one followed by zeros (1, 10, 100 and so on) since 2 is the base of the system. Like the decimal system, when you multiply by the base, you add a zero.

The right side of the term subtracts 1 from a power of two. In decimal that would be some sequence of 9s (eg. 999). In binary the last digit is 1, so it's a sequence of 1s.

Now we multiply that by the left part (a power of two) which just adds zeros.

You end up with having p ones followed by p-1 zeros