Complex formula?

[Jay]

Let's say I have a simple table with column headings of each month and I
have a starting value of 10,000 at the beginning of the year.

I want to reduce this value by a fixed percentage each month. However,
I know I want the end result to be 8,800 after the 12 monthly
reductions, which equates to -12% over the year, but what formula can I
use to determine what the fixed monthly percentage reduction should be?

I happen to know that it's -1.0596241% (trial & error got me that far).

But what formula can be used to extrapolate this from the known variables

I need the formula to also work if I need to reduce by another
percentage over the year. For example, if I need to reduce my starting
value by -20% over the year what fixed monthly percentage does this
equate to.

If anyone could help I would greatly appreciate it.

Many thanks,

Jason

 

[Erik Veldkamp]

The formula: (((end value)/(start value))^(1/12) - 1)*100%

There are appropiate financial calculation functions in Excel to get there.

Erik

 

[Ron Rosenfeld]

Let's say I have a simple table with column headings of each month and I
have a starting value of 10,000 at the beginning of the year.

I want to reduce this value by a fixed percentage each month. However,
I know I want the end result to be 8,800 after the 12 monthly
reductions, which equates to -12% over the year, but what formula can I
use to determine what the fixed monthly percentage reduction should be?

I happen to know that it's -1.0596241% (trial & error got me that far).

But what formula can be used to extrapolate this from the known variables

I need the formula to also work if I need to reduce by another
percentage over the year. For example, if I need to reduce my starting
value by -20% over the year what fixed monthly percentage does this
equate to.

If anyone could help I would greatly appreciate it.

Many thanks,

Jason

=RATE(12,,10000,-8800)
--ron