Number Format For Datagridview in C#

Number Format For Datagridview in C#

I want to set the datagridview values in number format. Currently I am
getting this:

I want something like this:

I have used this code:
dgvmain.DefaultCellStyle.Format = "#.##0";
And this code
dgvmain.Columns["Amount"].DefaultCellStyle.Format = "#.##0";
But neither of this working.