At the moment I'm sitting at the reference desk, about 3 hours into my 4 hour shift. (This is after working 8 hours at my day job, mind you.)
It's been a slow night, so I took advantage of the peace and quiet to create an Excel document to track my inventory, revenue, and expenses. (One of the many advantages of being a part-time librarian is being able to work on stuff like this during the free time you get when there aren't a lot of patrons!) The worksheet tracking inventory has a record for each item, and each record includes a sale date, sale price, shipping charge, and sales tax amount to be filled in as each item sells over the course of the year. The worksheet that tracks my sales gets all its information from the inventory sheet, but is broken down by month.
My attempt to make this work resulted in a 2 1/2 hour long battle with the "SUMIF" function, since I couldn't quite seem to get it to pull the numbers based on a date range. I did finally figure it out, thank goodness. I'm feeling pretty accomplished at the moment, though I can barely see straight after staring at the computer for so long.
If this works as planned, all I'll have to do is plug in numbers from here on out. Yay!