In Excel 2013, formulas now reside on the FORMULAS tab of the Ribbon.
On this tab, you can create and work with formulas in your workbook.
However, there are other places within Excel 2013 where you can use formulas.
When on the HOME tab, in the Editing group, you can use the AutoSum button to quickly add your data.
Also, when working in Excel 2013, you can work with formulas regardless of what tab you are on in the Ribbon. Simply do the following: