Basically how my spreadsheet works is it takes the dailies a movie has already made (so 15 days in this case), then extrapolates using the daily drops from the future days onward (so from day 16 onward in this case) of the movies on the left side to get a guesstimate domestic total. Then I use the current dom/int split to guess the WW total. It's not perfect, but just fun to throw in some comp links into my spreadsheet and it does it all. The graphic is the part that takes a while to make lol.

Here's a pic of a part of my spreadsheet