deleting cell values of datagridview

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C#

C#4.0

DataGridView

I have a datagridview. i want to select some cells which spreaded in different columns and rows. when i hit Delete key this cells should be clear. i could achieve this for cells of text type as follows (I use MS Access as the database and all fields are numbers)

if (e.KeyData == Keys.Delete)
                   {

                       foreach (DataGridViewCell cell in dataGridView1.SelectedCells)
                       {
                           // if keep column in text type in MS access
                           string i = "";
                           cell.Value = (object)i;


                       }

this really clear all deleted cells. but what shall i do if the cells are numbers . how i can assign null value to these numbers while deleting.

if (e.KeyData == Keys.Delete)
                    {

                        foreach (DataGridViewCell cell in dataGridView1.SelectedCells)
                        {
                            // if keep column in text type in MS access
                            int i =0;//here i want some null value
                            cell.Value = (object)i;

                            
                        }

the above code make all deleted cell with zeros . I want to avoid that situation. I dont want to place a zero for null.

another approach I did is

if (e.KeyData == Keys.Delete)
                    {

                        foreach (DataGridViewCell cell in dataGridView1.SelectedCells)
                        {
                            
                            cell.Value = cell.DefaultNewRowValue;

                            
                        }

but this do not work when i select cells of more than one row . how i can solve it;

please somebody help please......