Mathematical and Physical Journal
for High Schools
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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.


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