If you got over the basics, you would want to get over the insecurity of building solutions which barely cover your needs.
Keeping larger amounts of data is now becoming necessary, and you’d wish to keep it error-free.
How to overcome the fear that the logic you put in assembling your formulas is covering all aspects ? What if you overlooked a special situation ?
You don’t have such problems ? : Back to the beginners with you, then !!!
The process of learning mastering the spreadsheets has to be a test-and-error one. Please, believe me that nobody builds its solutions fail-proof. You only have problems which are solved provided that some restrictions are met. You are just learning now to name these restrictions. Please , refer to the series of examples for Late Payment Penalty, to see how you build progressively your applied solution.
Let’s meet and discuss in the Intermediate Users forum.