How to convert int array to int?

Question

What I would like to learn how to do is to convert an int array to an int in C#.

However I want to append the int with the values from the array.

Example:

Answer 1

int output = array
    .Select((t, i) => t * Convert.ToInt32(Math.Pow(10, array.Length - i - 1)))
    .Sum();