Gary''s Student wrote:
Always use (start-finish)/start
if start is in A1 and finish is in B1 then the % change in C1

I disagree. When "finish" is greater then "start", most people
expect a positive percentage increase. To that end, "always
use" (finish - start) / start.

For example, if "start" is 100 and "finish" is 110, we expect a
10% increase: (110-100)/100 = 10/100 = 10%. If "finish" is 90,
we expect a 10% decrease, i.e. a -10% "increase":
(90-100)/100 = -10/100 = -10%.

"Neil R" wrote:
I am looking for a formula that tells me % of increase or decrease,
The problem is that some of my numbers are negitive eg. -147.80
has decreased to -785.00 I am looking for the % to be a negitive

I think your expectation is correct. Someone else provided
one formulation that would work, although it can be simplified
(where A1 is "start" and B1 is "finish"):

=IF(A1 0, (B1-A1)/A1, -(B1-A1)/A1)

But if you can have mixed positive and negative results, I
would also cover the case where "start" is zero, e.g:

=IF(B1 < A1, -1, 1) * IF(A1 < 0, ABS((B1-A1)/A1), 100%)

Of course, the choice of 100% is arbitrary.