Question

How can I calculte the sum of integer and float values stored in a dataGridView column on a button click and store the show in a textbox ?

Answer 1

int sum = 0;

foreach (DataGridViewRow row in dataGridView.Rows)
{
    //here 0 is the index of columns you want to get values from 
    // you can also use column name instead of index
    sum += (int) row.Cells[0].Value;
}

//for showing the user message box
MessageBox.Show("Sum of all the values is {0}", sum.ToString());