Count function Issue

[Lamda]

Hey Guys,

I'm having an issue with a Count function that i'm hoping you all could help me with. I have a column of about 100k rows that i'm looking for just dupes and then a count of those so i'm basically removing anything that comes back with a count of 1. So I create a count column and run the following function

=Countif(A2:A100000,A2)

so i'm giving my range of the 100k rows and then selecting the first cell to run a count on it. This comes back with a number and then I drag the formula all the way down to run through the other 100k.

The issue i'm seeing is that i'm getting a count of more than 1 in some cases. Column A is an ID so for example for ID 345 I will get a count of 3. I will then go back to my raw data and look up ID 345 and I only show 1 row's worth of data. Why did it come back with a count of 3? Am I not using the count function correctly?

Thanks!

 

[Joe4]

First off, if you want to copy that formula down, you will need to lock the range you are searching using absolute range references, i.e.
=Countif(A$2:A$100000,A2)

otherwise, the row numbers will increment as you move down the page.