C# Midpoint Rule (Rectangle Method)

Implementation of Midpoint Rule (Rectangle Method) (Integral Approximation) written in C#.

Enter beginning of interval: -2
Enter end of interval: 2
Enter number of iterations: 1000000
Integral is equal to: 5.33333333334422

using System;

// ? 2018 TheFlyingKeyboard and released under MIT License
// theflyingkeyboard.net
namespace MidpointRule
{
    class Program
    {
        static void Main(string[] args)
        {
            double intervalBegin;
            double intervalEnd;
            int iterations;
            double integral = 0;
            double step;

            Console.Write("Enter beginning of interval: ");
            intervalBegin = Convert.ToDouble(Console.ReadLine());

            Console.Write("Enter end of interval: ");
            intervalEnd = Convert.ToDouble(Console.ReadLine());

            Console.Write("Enter number of iterations: ");
            iterations = Convert.ToInt32(Console.ReadLine());

            step = (intervalEnd - intervalBegin) / iterations;

            for (int i = 1; i <= iterations; ++i) {
                integral += step * Function(intervalBegin + (i - 1) * step);
            }

            Console.WriteLine("Integral is equal to: " + integral);
            Console.ReadKey();
        }

        private static double Function(double x)
        {
            return x * x;
        }
    }
}