I have opportunities with line items/products that have a "start date" field in one month and a "close date" field in another. If I know the total number of days where the products are active and the averaged amount for each day - how do I calculate the amount per month? 

Ex. Opp A with Product B
Start Date: Jan 30
End Date: Feb 4
Total Days: 5 (2 in Jan, 3 in Feb)
Average Amount per Day: $10

How do I separate out the $20 for Jan and the $30 in Feb from the same opportunity? Ideally I'd like to run a report and see the opp amounts calculated for each month...

Is it possible to create an opportunity report that reviews opportunities by a date range field (like January-February) instead of a singular date field (like "Created Date")?

Simply stated, my goal is to write an accrual report that lists all closed/won opportunities by each month (with each month including in an opportunity only if any of its products are active during that month). I do have a field for the number of days an opportunity runs (product end date - start date) as well as the average price per day (total opp price / # of days), but I can't figure out how to accomodate the opportunities which run for mulitple months. Hopefully this explanation makes sense. So:

1) How do I create a field that indicates the sum of the total months/dates that an opportunity and its products cover? I figured I'd use that field to sort active opps in the report, but should I be heading in a different direction? 

2) Once I know the total dates/months, how do I split an opportunity within a report to reflect the $ spent per each month? For example, let's say there's an opportunity with a total price $1500 has a product that runs 5 days in January and 10 in February. How do I correctly note that the opp is active in January/February and show that the opp is credited $500 for January and $1000 for February?