Calculate 2 rows given string formula (Grid Batch edit mode)

[Mr]

Hi,

please help.

<telerik:GridBoundColumn DataField="ID" HeaderStyle-Width="80px" HeaderText="ID"
                                UniqueName="ID">
</telerik:GridBoundColumn> 

<telerik:GridNumericColumn DataField="Value" HeaderStyle-Width="80px" HeaderText="Value"
                                UniqueName="Value">
</telerik:GridNumericColumn> 

<telerik:GridBoundColumn DataField="Formual" HeaderStyle-Width="80px" HeaderText="Formual"
                                UniqueName="Formual">
</telerik:GridBoundColumn> //formula example 1+2 . 1 and 2 are an ID and those get values from GridNumericColumn and set it to column "Value" where Column formula exist

Many Thanks