Not all perfect numbers end in 6 or 28.

Question

Quizplus · Accepted Answer

All known perfect numbers indeed end in 6 or 28 when written in decimal form. This is because every even perfect number can be written in the form 2^(p-1)*(2^p - 1), where both 2^p - 1 and p are prime (these primes are known as Mersenne primes). The smallest even perfect number is 6, which is 2^(2-1)*(2^2 - 1), and the next is 28, which is 2^(3-1)*(2^3 - 1). All subsequent even perfect numbers follow a similar pattern, leading to their last digits being either 6 or 28. There are no known odd perfect numbers.

Not All Perfect Numbers End in 6 or 28