Cell Formatting In DataGridView On DataBindingComplete

I am having problems with a requirement on one of my projects at work. What I am doing is binding a datatable to a DataGridView(DGV)'s datasource. I then loop through the DataGridView and check if the cell as either 1 * or 2 ** in its value and format those cells with a tooltip and a red background. If I use a button event to trigger this everything works perfectly fine. But if I want this to occur automatically when the form loads using the DataBindingComplete event it does not work correctly. The problem was DataBindingComplete was firing multiple times. I read this SO question which gave me a couple options to try and none worked. Here is the code:

public partial class TestForm2 : Form
{
    private DataTable dt;
    private int methodCalls = 0;
    private bool isFormatted = false;

    public TestForm2()
    {
        InitializeComponent();
        buildDataTable();
        dataGridView1.DataBindingComplete += dataGridView1_DataBindingComplete;
    }

    private void TestForm2_Load(object sender, EventArgs e)
    {
        bindData();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        formatDataGridView();
    }

    private void bindData()
    {
        dataGridView1.DataSource = dt;
    }

    private void dataGridView1_DataBindingComplete(object sender, DataGridViewBindingCompleteEventArgs e)
    {
        //If this code is commented out the program will work just fine 
        //by just clicking the button

        //This was added to prevent formatDataGridView from executing more
        //than once.  Even though I unreg and rereg the event handler, the 
        //method was still being called 3 - 4 times. This successfully
        //prevented that but only the *'s were removed and no red back color
        //added to the cells.
        if(!isFormatted)
        {
            formatDataGridView();
        }
    }

    private void buildDataTable()
    {
        dt = new DataTable();

        dt.Columns.Add("col1");
        dt.Columns.Add("col2");
        dt.Columns.Add("col3");
        dt.Columns.Add("col4");
        Random randNum = new Random();
        for(int i = 0; i < 10; i++)
        {
            DataRow dr;
            object[] rowItems = new object[dt.Columns.Count];

            for(int j = 0; j < dt.Columns.Count; j++)
            {
                int number = randNum.Next(1, 20);

                if(number % 7 == 0)
                {
                    rowItems[j] = number + "*";
                }
                else if(number % 5 == 0)
                {
                    rowItems[j] = number + "**";
                }
                else
                {
                    rowItems[j] = number;
                }
            }

            dr = dt.NewRow();
            dr.ItemArray = rowItems;
            dt.Rows.Add(dr);
        }
    }

    private void formatDataGridView()
    {
        // I noticed that I needed to unregister the event handler to 
        // prevent DataBindingComplete from firing during the format
        dataGridView1.DataBindingComplete -= dataGridView1_DataBindingComplete;
        foreach(DataGridViewRow row in dataGridView1.Rows)
        {
            string originalCell;
            string reformattedCell;

            if(row.Cells["col1"].Value != null)
            {
                originalCell = row.Cells["col1"].Value.ToString();

                if (originalCell.Count(c => c == '*') == 2)
                {
                    reformattedCell = originalCell.Replace("**", "");

                    row.Cells["col1"].Value = reformattedCell;
                    row.Cells["col1"].Style.BackColor = Color.Red;
                    row.Cells["col1"].ToolTipText = "Divisible by 5";
                }

                else if (originalCell.Count(c => c == '*') == 1)
                {
                    reformattedCell = originalCell.Replace("*", "");

                    row.Cells["col1"].Value = reformattedCell;
                    row.Cells["col1"].Style.BackColor = Color.Red;
                    row.Cells["col1"].ToolTipText = "Divisible by 7";
                }

                else
                {
                    //do nothing
                }
            }

            if (row.Cells["col2"].Value != null)
            {
                originalCell = row.Cells["col2"].Value.ToString();

                if (originalCell.Count(c => c == '*') == 2)
                {
                    reformattedCell = originalCell.Replace("**", "");

                    row.Cells["col2"].Value = reformattedCell;
                    row.Cells["col2"].Style.BackColor = Color.Red;
                    row.Cells["col2"].ToolTipText = "Divisible by 5";
                }

                if (originalCell.Count(c => c == '*') == 1)
                {
                    reformattedCell = originalCell.Replace("*", "");

                    row.Cells["col2"].Value = reformattedCell;
                    row.Cells["col2"].Style.BackColor = Color.Red;
                    row.Cells["col2"].ToolTipText = "Divisible by 7";
                }

                else
                {
                    //do nothing
                }
            }

            if (row.Cells["col3"].Value != null)
            {
                originalCell = row.Cells["col3"].Value.ToString();

                if (originalCell.Count(c => c == '*') == 2)
                {
                    reformattedCell = originalCell.Replace("**", "");

                    row.Cells["col3"].Value = reformattedCell;
                    row.Cells["col3"].Style.BackColor = Color.Red;
                    row.Cells["col3"].ToolTipText = "Divisible by 5";
                }

                else if (originalCell.Count(c => c == '*') == 1)
                {
                    reformattedCell = originalCell.Replace("*", "");

                    row.Cells["col3"].Value = reformattedCell;
                    row.Cells["col3"].Style.BackColor = Color.Red;
                    row.Cells["col3"].ToolTipText = "Divisible by 7";
                }

                else
                {
                    //do nothing
                }
            }

            if (row.Cells["col4"].Value != null)
            {
                originalCell = row.Cells["col4"].Value.ToString();

                if (originalCell.Count(c => c == '*') == 2)
                {
                    reformattedCell = originalCell.Replace("**", "");

                    row.Cells["col4"].Value = reformattedCell;
                    row.Cells["col4"].Style.BackColor = Color.Red;
                    row.Cells["col4"].ToolTipText = "Divisible by 5";
                }

                else if (originalCell.Count(c => c == '*') == 1)
                {
                    reformattedCell = originalCell.Replace("*", "");

                    row.Cells["col4"].Value = reformattedCell;
                    row.Cells["col4"].Style.BackColor = Color.Red;
                    row.Cells["col4"].ToolTipText = "Divisible by 7";
                }

                else
                {
                    //do nothing
                }
            }
        }
        // Reregistering the event handler
        dataGridView1.DataBindingComplete += dataGridView1_DataBindingComplete;
        isFormatted = true;
        methodCalls++;
        MessageBox.Show("Method Calls: " + methodCalls);
    }
}

I am not sure how to get around this problem but there has to be a way. I am unfamiliar with DataBindingComplete until recently so I am sure to learn something here. Thanks for the help everyone and helping me learn something new!