请帮我调试一下我的计算器程序

我想做一个计算器。当我代入25 * 4/10时，25除以4。以下是我认为可能存在问题的部分代码:

    private void button16_Click(object sender, RoutedEventArgs e)
    {
        string[] calCulation = CALCULATION.Text.Split('-', '+', '/', 'X');
        int numOfItems = calCulation.Length;
        int count = 1;
        char[] Arius = new char[Hey.Length];
        foreach(char words in Hey)
        {
            int outlie = 0;
            Arius[outlie] = words;
            outlie++;
        }
        decimal final = 0M;
        decimal[] calCulate = new decimal[numOfItems];
        int countfreak = 0;
        foreach (string word in calCulation)
        {
            calCulate[countfreak] = Convert.ToDecimal(word);
            countfreak++;
        }
        int counting = 1;
        int countinghey = 0;
        decimal final2 = calCulate[0];
        while(count < numOfItems){

            switch(Arius[countinghey])
            {
                case 'X':
                    /*
                        final2 += final * calCulate[counting -1];
                        final2 = final2 * calCulate[counting];
                     */
                    final2 = final2 * calCulate[counting];
                    break;
                case '-':

                        final2 = final2 - calCulate[counting];
                    break;
                case '+':

                        final2 = final2 + calCulate[counting];
                    break;
                case '/':

                        final2 = final2 / calCulate[counting];
                    break;
            }
             counting++;
             countinghey++;
             count++;
        }
        CALCULATION.Text = Convert.ToString(final2);
    }
    public bool Parshing(string value, string typee)
    {
        int hixty = value.Length;
        string six = value.Substring(hixty - 1, value.Length - hixty + 1);
        int lam;
        bool result = Int32.TryParse(six, out lam);
        if (result == true||six == "")
        {
            CALCULATION.Text += typee;
            Hey += typee;
        }
        else
        {
        }
        return result;
    }

string[] calCulation = CALCULATION.Text.Split('-', '+', '/', 'X');

 25 * 4 / 10

string[] calCulation = CALCULATION.Text.Split('-', '+', '/', '*');