A comment can be added to a formula by adding an N function. Or
=Formula+N(“YourTextHere”)

The =N() function returns the number for a given cell. For instance if 1% is in a percentage formatted cell A1, putting =N(A1) in another cell will return the number .01

However when the N function can’t convert the given information it returns 0. So to add a comment to a formula we simply add an N function to the formula, which in turn returns zero, and doesn’t alter the formula in most cases.

This picture demonstrates the use of the N function, added to an existing formula to provide a comment.