example.cs

using System;
class Program
    {
        static void Main()
        {
            int z = 42;
            int x = Foo(z);
            Console.WriteLine($"{x}, {z}");
            // get: 871, 42
            // expected: 871, 46

        }
        static int Foo(int j)
        {
            int result = 1;
            for (int i = 0; i < 4; i++)
            {
                result += 5 * j++;
            }
            return result;
        }
    }