Then click the tables Layout contextual tab in the Ribbon. In the Formula box check the text between the parentheses to make sure Word includes the cells you want to sum and click OK. Add a Formula Following are the simple steps to add formula in a table cell available in Word document.
Click the table cell in which you want to insert a formula.
If the cell you selected is at the bottom of a column. From the top menu select Insert Object Create New. If the cell you selected is at the bottom of a column. Place your insertion point in an empty cell at the bottom of the Total column insert an extra row if you need to.