C# loop into list with specific conditions

I have a function which gets 7 integers in parameters, should check all possible combinations of 5 numbers (using these 7 numbers) and return true if at least 1 combination of 5 numbers is equal to 100.

That is how I managed to get this done, I feel my way is bad and completely inefficient. It takes few seconds to run such a simple task, which shows how badly I wrote this. If possible I would like to get some advices about finding the proper way of doing it, I guess I need to replace nested loops by something else, more efficient.

private bool test_condition_equal100(int number1, int number2, int number3, int number4, int number5, int number6, int number7) 
        {
            List<int> totalnumbers = new List<int>()
            {
                number1,number2,number3,number4,number5,number6,number7
            };
           

            for(int i = 0; i < 7; i++)
            {
                for (int j = 0; j < 7; j++)
                {
                    for (int k = 0; k < 7; k++)
                    {
                        for (int l = 0; l < 7; l++)
                        {
                            for (int m = 0; m < 7; m++)
                            {
                                if ((totalnumbers(i) + totalnumbers(j) + totalnumbers(k) + totalnumbers(l) + totalnumbers(m) == 100))
                                {
                                    return true;
                                }
                            }
                        }
                    }
                }
            }

            return false;