Five
coworkers want to know what the average of all their salaries is, but refuse to
reveal ANY information about their own salaries to their coworkers. How can
they calculate the average?

Let's call the workers: Worker 1,
Worker 2, Worker 3, Worker 4 and Worker 5.

Hints:What if one of the workers picks a random number that only he knows? How could this help?

**Solution**

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Worker 1 picks a random positive number
N (which he doesn't tell anybody), add his salary to it, and writes this number
on a piece of paper which he hands to Worker 2.

Worker 2 adds his salary to this
number, writes the new number on a different piece of paper, and hands it to
Worker 3.

Worker 3 does the same and hands a new
paper to Worker 4, who does the same and hands a new paper to Worker 5, who
does the same and hands a new-paper back to Worker 1.

The number written on this final piece
of paper will be (N + the-sum-of-every body’s-salary).

So Worker 1 simply subtracts N from
this number and divides this final number by 5, which is the average salary. At
no point did any worker gain any information about anyone else's salary.

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