Find all possible integer values of n such that $12n^2 + 12n + 11$ is a 4-digit number with all 4 digits equal.
Threr is only ONE value of n = 21 that satisfies the expression:
Sub 21 for n =12*21^2 + 12*21 + 11 =5,292 + 252 + 11 =5,555
