cash receipt forecasting

[njbeancounter]

I am trying to see into the future based on the past...

I have several worksheets...'receipts' 'write offs' 'totals'

column a contains sales amounts by date
columns b though aw contains amounts of either cash or wite off, by date
in 'totals' I am summing the receipts and write offs, by date, in order to calculate the amount of sales, by date, that remains unpaid. From this info, I want to calculate the % of receipts for the first day after the sale, the total % received for the second day, etc...

for instance, sales on 3/1/11 was $100,000
receipts on 3/2 was $5,000, or 5% of the total sales
receipts on 3/3 was $6,000, for a total of 11% of total sales


At this point I am looking for suggestions as to the most efficient way to summarize, as I have finally been able to import all the raw date...

thanks