In complex models, it is important to write comments explaining how the formulas work. But the limitation of Excel's Insert Comment feature is that you must type the entire comment in a textbox. There is an alternative. You can use N() formula to insert your comments inside a formula directly. Let's see how.
- While typing your actual formula, type +N(
- Type your comment and make sure it is between quotes "Annual interest rate divided by 12"
- Type ) and press Enter to complete the formula
Excel doesn't support adding comments into formulas by default. However, you can add them by using N function which converts a value to a number. It means while regular numbers return same values, dates return serial numbers and Boolean values returns 1/0.
However, string values returns 0. This behavior allows us to add comments into formulas by using one of the basic mathematical rules. The number 0 is non-effective in addition and subtraction operations. Of course, the drawback is that it can only be used for formulas that returns numeric values.
Let's see how Excel calculates our PMT formula while we can read comments on each parameter.
How we see:
(B3/12)+N("Annual interest rate divided by 12"),
B4+N("Number of periods (months)"),
How Excel sees:
=N("Annual interest rate divided by 12")