Searching for an specific function.

[Guido94]

Hi all. I'm from Argentina, therefore it may be a bit difficult to understand me. 

I'm working in a refrigeration business, i have a wide range of products with their respective prices. I need to apply a percentage to these prices each day (due to dollar increase). I need a formula, to always apply a different percentage to a NEW amount.

I don't need a function to apply a simple percentage because that's easy. I need one to apply it to always the new amount obtained by adding a percentage.

Example:

100 + 5% = 105

105 + 10% = 115.5

Assuming that in the list of prices 100 would change for 105 and a new percentage will be always applied to the LAST number.

Thank you so much for trying to help me. 

[#2 · Accepted solution]

I don't have time to address this in depth, so maybe somebody else will. If I were to spend time on it, though, I'd start with the premise that what you need isn't so much a formula; rather, you need a database that is updated each day, based on data for each product for the prior day.

I'd have some questions for you. To start with, though there may be more:
1) is it really each and every day?
2) is every product price changed every day?
3) is the percent change the same for every product every day, or do some products change more than others? (If it's purely an exchange rate or inflation rate issue, that's easier.)

I'd create a database with each row containing a line with columns like:
Date, Product, Price
THis is the simplest way to keep a history and a record of current price for each day. Then you'd apply the formula you know to the prior day's prices, and just add one more row with the new day's date.

[#3]

You obviously have all your items listed and the price for your stock items.
I would suggest that when you write your price formulas you have the price, then instead of inserting a percentage amount you put a separate data box e.g. A57, and your formula would look like: =sum(5.78+A57). Every day you would change A57 say from 5% to 6.5% or whatever and then all the prices would change automatically. Cheers from Charlene in Darwin Australia