Problem B. 4770. (February 2016)
B. 4770. What may be the last digit of a positive integer \(\displaystyle n\ge 3\) if \(\displaystyle n+n^{2}
+\dots+n^{2n3}  4\) is a prime?
(4 pont)
Deadline expired on 10 March 2016.
Statistics:
122 students sent a solution.  
4 points:  93 students. 
3 points:  21 students. 
2 points:  6 students. 
1 point:  1 student. 
Unfair, not evaluated:  1 solution. 
