Problem B. 4770. (February 2016)
B. 4770. What may be the last digit of a positive integer \(\displaystyle n\ge 3\) if \(\displaystyle n+n^{2} +\dots+n^{2n-3} - 4\) is a prime?
(4 pont)
Deadline expired on March 10, 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 solutions.
Problems in Mathematics of KöMaL, February 2016