On the Table Tools Layout tab click the Formula button. If the cell is not empty delete its contents. In the Formula box check the text between the parentheses to make sure Word includes the cells you want to sum and click OK.
You can type in the Formula box select a number.
Also if you are already familiar with Excel then using the formulas in Word will be a piece of cake. Instructions on How to Insert Table Formulas in Word To insert table formulas in Word click into the table cell where you want to show the answer to the formula. Step 2 Now click the Layout tab and then click the Formula button. Click on the Insert tab and then click on Table.