Limit of 40 items then go to its corresponding category

[superdre]

Hi, i wonder if this is possible, i´ve never done it .

I need to have a menu let´s say "NEW PRODUCTS" with a list of... 40 items from different categories (cat1 / cat2 / cat3/ cat4). I need to:

When i add the product nº 41, i need this product to be the nº 1, and the old product nº40 go to its corresponding category (for example cat2) and then if i add product nº 42 (this will be nº 2) and the last on the list will go to its corresponding category.

I know it sounds messy but does anyone imagine how to do this?
regards.
Roxana.