Because Equation Editor isnt available in Excel for the web you wont be able to insert them. It will also open two tabs the Drawing tools and Equation tools editor in the ribbon at the top of our worksheet. Your add-in will have the extension.
When you open a workbook that has equations they wont be shown.
If you have the Excel desktop application you can use the Open in Excel button to open your workbook to view and insert equations there. My formulas are getting longer and longer. Because Equation Editor isnt available in Excel for the web you wont be able to insert them. Value c4 4.