So, you want to have a GridDataBoundGrid where if your user enters 10+20 in a cell, the cells shows 30 and 30 is saved into the datasource of the grid.
I think the simplest way to do this is to use Essential Calculate. You can create a CalcQuick object.
this.calculator = new Syncfusion.Calculate.CalcQuick();
Then handle the CurrentCellValidating event.
private void gridDataBoundGrid1_CurrentCellValidating(object sender, CancelEventArgs e)
{
GridCurrentCell cc = this.gridDataBoundGrid1.CurrentCell;
cc.Renderer.Control.Text = calculator.ParseAndCompute(cc.Renderer.ControlText);
}