[C#] Methods/ Task 13 - Many In One

using System;
class ManyInOne
{
    //Reverse Method
    static string Reverse(decimal number)
    {
        string newNum = "";
        string temp = number.ToString();
        for (int i = temp.Length - 1; i >= 0; i--)
        {
            newNum += temp[i] + "";
        }
        return newNum;
    }

    //Calculates Average
    static decimal AverageCalculates(decimal[] arr)
    {
        decimal sum = 0m;
        decimal average = 0m;
        foreach (int number in arr)
        {
            sum += number;
        }
         average += (sum / arr.Length);
        return average;
    }

    //Calculatesa linear equation
    static float LinearEquation(float a, float b)
    {
        float linear = 0f;
        if (a == 0)
        {
            Console.WriteLine("error");
        }
        if (a != 0)
        {
            linear = (-b) / a;
        }
        return linear;
    }

    //Filling the array
    static void FillTheArray(decimal[] arr)
    {
        for (int i = 0; i < arr.Length; i++)
        {
            arr[i] = int.Parse(Console.ReadLine());
        }
    }

    static void Main()
    {
        Console.WriteLine("What would you like to do:");
        Console.WriteLine("1. Reverse digits of a number.");
        Console.WriteLine("2. Calculates the average of a sequence of integers.");
        Console.WriteLine("3. Solves a linear equation a * x + b = 0.");
        Console.Write("Enter the number of task you chose: ");
        byte choose = byte.Parse(Console.ReadLine());

        switch(choose)
        {
            case 1:
                Console.WriteLine("Enter a number to reverse it's digits:");
                decimal number = decimal.Parse(Console.ReadLine());
                string reverseNum = Reverse(number);
                Console.WriteLine(reverseNum);
                break;
            case 2:
                Console.WriteLine("How many numbers you want to be in your sequence: ");
                int count = int.Parse(Console.ReadLine());
                decimal[] sequence = new decimal[count];
                FillTheArray(sequence);
                decimal average = AverageCalculates(sequence);
                Console.WriteLine("The average of your numbers is {0}", average);
                break;
            case 3:
                Console.WriteLine("Enter two numbers:");
                float a = float.Parse(Console.ReadLine());
                float b = float.Parse(Console.ReadLine());
                float result = LinearEquation(a, b);
                Console.WriteLine("The result is {0}", result);
                break;
            default:
                Console.WriteLine("Wrong Enter!");
                break;
        }
        Main();

    }
}