Credit System

using System;

namespace CreditSystem
{
    internal class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());

            double totalGrades = 0;
            double totalCredits = 0;

            for (int i = 0; i < n; i++)
            {
                int number = int.Parse(Console.ReadLine());
                int grade = number % 10;
                double credit = (int)number / 10;

                totalGrades += grade;

                if (grade == 2)
                {
                    credit = 0;
                }
                else if (grade == 3)
                {
                    credit *= 0.50;
                }
                else if (grade == 4)
                {
                    credit *= 0.70;
                }
                else if (grade == 5)
                {
                    credit *= 0.85;
                }

                totalCredits += credit;
            }

            Console.WriteLine($"{totalCredits:f2}\n{totalGrades / n:f2}");
        }
    }
}


Решение с тернарен оператор:

using System;

namespace CreditSystem
{
    internal class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());

            double totalGrades = 0;
            double totalCredits = 0;

            for (int i = 0; i < n; i++)
            {
                int number = int.Parse(Console.ReadLine());
                int grade = number % 10;
                double credit = (int)number / 10;

                totalGrades += grade;

                credit *=
                    grade == 2 ? 0 :
                    grade == 3 ? 0.50 :
                    grade == 4 ? 0.75 :
                    grade == 5 ? 0.85 : 1;

                totalCredits += credit;
            }

            Console.WriteLine($"{totalCredits:f2}\n{totalGrades / n:f2}");
        }
    }
}