Matrix multiplication

using System;
using System.Collections.Generic;
using System.Linq;

namespace Demo
{
    class Program
    {
        static void Main(string[] args)
        {
            //variant1
            var matrixA = new int[,]
            {
                { 1, 2, 3 },
                { 4, 5, 6 },
                { 7, 8, 9 }
            };
            var matrixB = new int[,]
            {
                { 0, 1, 0 },
                { 7, 3, 4 },
                { 2, 6, 3 }
            };

            var matrixC = new int[3, 3];
            int sum = 0;
            for (int row = 0; row < matrixA.GetLength(0); row++)
            {
                for (int col = 0; col < matrixB.GetLength(1); col++)
                {
                    for (int k = 1; k <= 3; k++)
                    {
                        sum += matrixA[row, k - 1] * matrixB[k - 1, col];
                    }
                    matrixC[row, col] = sum;
                    sum = 0;
                }
            }

            for (int i = 0; i < matrixC.GetLength(0); i++)
            {
                for (int j = 0; j < matrixC.GetLength(1); j++)
                {
                    Console.Write(matrixC[i, j] + " ");
                }
                Console.WriteLine();
            }

            //Variant2
            var matrixA = new int[,]
            {
                { 1, 2, 3 },
                { 4, 5, 6 },
                { 7, 8, 9 }
            };
            var matrixB = new int[,]
            {
                { 0, 1, 0 },
                { 7, 3, 4 },
                { 2, 6, 3 }
            };

            var matrixC = new int[3, 3];
            for (int row = 0; row < matrixA.GetLength(0); row++)
            {
                for (int col = 0; col < matrixB.GetLength(1); col++)
                {
                    matrixC[row, col] = 0;
                    for (int k = 0; k < 3; k++)
                    {
                        matrixC[row, col] += matrixA[row, k] * matrixB[k, col];
                    }
                }
            }

            for (int row = 0; row < matrixC.GetLength(0); row++)
            {
                for (int col = 0; col < matrixC.GetLength(1); col++)
                {
                    Console.Write(matrixC[row, col] + " ");
                }
                Console.WriteLine();
            }
        }
    }
}