MathDB

At the round table there are

10

students. Every of the students thinks of a number and says that number to its immediate neighbors (left and right) such that others do not hear him. So every student knows three numbers. After that every student publicly says arithmetic mean of two numbers he found out from his neghbors. If those arithmetic means were

1

2

3

4

5

6

7

8

9

and

10

, respectively, which number thought student who told publicly number

6

Problem Statement