Calculating Across Tables
You can perform calculations that span across more than one table in a text document.

Open a text document, insert two tables, and type numbers in a few cells in both tables.

Place your cursor in an empty cell in one of the tables.

Press F2.

In the =SUM.
, enter the function that you want to perform, for example, 
Click in a cell containing a number, press the plus sign (+), and then click in a different cell containing a number.

Press Enter.