This page decribes how to show formulas in Excel, for a whole worksheet, or how to just show the formula in a single Excel cell.
If you want to show the formulas in all of the cells in your spreadsheet, the easiest way to do this is through the keyboard combination:
I.e. press the control key, and while holding this down, press the ` key.
Note that, on many keyboards, the ` key is at the top left of the keyboard, next to the number 1.
To hide the formulas again, simply repeat the same key combination (i.e. press CTRL-`)
If you want to show a formula in a single Excel cell, you can do this by simply inserting an apostrophe at the start of the cell.
I.e. for a cell with the simple formula =TODAY() you would insert the apostrophe as follows:
This forces the cell to display the formula, rather than its result.