You can use the Formula command Table menu or press CTRLF9 to insert a field in a table or in regular text. On the Insert tab in the Text group select the Quick Parts drop-down list and the click on Field. First type O then if youre on the home tab you should see a little button with the symbol X2 with 2 being a subscript to X and it should.
To get started bring the cursor where you want to insert an equation or formula in your Word document.
To insert a formula do the following. Thanks to a new free add-in for Word you can now insert high-quality chemistry formulas and diagrams directly from the Ribbon in Word. This tutorial explains the easy way to create equations in Microsoft Office Word Document Facebook. Click the Equation button in the Symbols group.