Please try this out handling the PreRender event of the RadGrid to format the cell which is largest among all rows of the columns added in array and let me know if this helps for you :-
protected void MyRadGrid_PreRender(object sender, EventArgs e)
{
string[] columns = { "TaxID", "Tax1", "Tax2", "Tax3" };
foreach (string colName in columns)
{
int i = -1;
decimal max = decimal.MinValue;
foreach (GridDataItem dtItem in MyRadGrid.MasterTableView.Items)
{
decimal currentNo = decimal.Parse(dataItem[colName].Text);
if (currentNo > maxNumber)
{
max = currentNo;
i = dtItem.ItemIndex;
}
}
if (i >= 0)
{
GridTableCell gtCell = (MyRadGrid.Items[i] as GridDataItem)[colName] as GridTableCell;
gtCell.BackColor = System.Drawing.Color.Red;
}
}
}
Hope this will definitely be of help.