Right I'll reply in this one so that it gets bumped to the top and the other one you posted stays unanswered so other folk will look at it...

Let's just clarify what you're asking first...

Lets say you took the following amounts in 4 months.

Month Amount

-- 1 --- 1000

-- 2 --- 2000

-- 3 --- 1500

-- 4 --- 1800

Total = 6300

And you want to know how to scale it down so that can see how much you would need to earn each month if you wanted the same final total in say, 3 months. Right?

I can't formalize a way yet but I'll show you what I'm thinking...

Have a look at the picture attached.

Each box on the graph represents the monthly takings. (We'll call these old month)

The boxes below the graph represent the new rescaled months. (Call these new months)

What to do is look at each new month and see what each box covers, this is how much you need to earn that month...

So, the amount you need to earn for month 1 is...

For month 2...

For month 3

How did I do this? Draw lines up from the new months boxes up to the graph and you'll see for example, new month 1 covers all of old month 1's amount + a fraction of old month 2's amount.

Do this with the rest of the new months and you get how much you need for each new month.

Just as a check, if I add up the above totals I get...

I'll try and formulate a way for you to do this quickly with your large scale one...