Mathematical and Physical Journal
for High Schools
Issued by the MATFUND Foundation
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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.

### 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