Click in a cell that should contain the sum of the rows. Click the blank cell you want to show the calculated result then click layout Formula. If you were to simply click OK you will see the value we are looking for in the cell 30.
To reference the contents of a table cell type the cell references in the formula.
For instance we have included a document containing table. You can type in the Formula box select a number. In order to insert a table navigate to Insert tab and click Table. Now select the number of rows and columns as shown in the figure below.