There are 87 square numbers that use every digit (base 10, no leading zeroes)) exactly once.
(In reply to re(2): Pencil and Paper solution (spoiler)
by Steve Herman)
1 in 10 random numbers end in the same two digits. But only 1/100 squares do.
Does that get you closer?
Posted by Jer
on 2017-04-16 18:18:39