Psst … did you hear that 14 is the smallest number n such that n and 2n end with the same digit? Or that 27 is the smallest of only two known cubes made up of prime digits? At this site run by a PhD who won the gold medal at the International Math Olympiad, you enter any positive integer below 9,999 to get the inside dirt — exploring numerical phenomena like hungry numbers, Mersenne primes, and 47 more. It’s TMZ for mathletes!