Are you allowed to sort the data, as well as taking the absolute
value? If so, then you are looking for pairs of numbers in adjacent
cells. Assuming that you have your ABS formula in column B, starting
with B1, and that you have sorted the data by column B, then put this
formula in C1:

=IF(B1=B2,"yes1","no")

and this one in C2:

=IF(AND(B2=B1,C1="yes2"),IF(B2=B3,"yes1","no"),IF( B2=B1,"yes2",IF(B2=B3,"yes1","no")))

Copy this formula down column C by double-clicking the fill icon (the
small black square in the bottom right corner of the cursor. It will
give you pairs of "yes1"/"yes2" down the column indicating paired
duplicates, and the occasional "no" meaning a single unpaired (unique)
value.

If you wanted to use conditional formatting on the values in column A,
then you can use Formula Is and then =LEFT(C1,3)="yes" and set your
colour.

I've just realised that this doesn't necessarily pair +10 with -10, so
if you have, say, three +10s and one -10 this would indicate all four
10s would be paired - does this matter?

If you wanted the data in the original order, then you should first
enter a simple sequence in column D (say), i.e. 1, 2, 3, 4 etc before
sorting the data (including column D) on column B and using the
formulae. Then fix the values in column C and re-sort the data by
column D to get it back to the original sequence - column D can then
be deleted.

Anyway, hope this helps.

Pete

On Sep 28, 9:41 pm, wrote:
Also, to clarify, the reason i was asking about two columns was
because i used absolute value on all of the negative numbers and put
them in a separate list next to the positive ones to find EXACT
matches. But if there is a way in which this wasnt necessary, that
would be far more ideal.

Thanks again guys!