I've found a four-digit number ABCD
such that ABCD=(A+B+C+D)3
What is it ?
Is it unique?
(In reply to Paper & Pencil solution (spoiler)
by Steve Herman)
It must be clever to realize Mod 9. But 10 < A + B + C + D < 22. Therefore, it's quick even to try and see each of these.
Posted by chun
on 2017-06-15 15:09:22