Counting multiple instances - same value

Hi,

I have a spreadsheet with approx 20,000 6-digit number values in column A, and no other data on the spreadsheet.

I am looking for an expression that will let me display any values that are repeated in the list.

For example; the data -

123456
456789
741852
963369
456789

After running the expression, I would like to display in another column, or worksheet the value 456789 as it is in the list twice.

Can anyone tell me what expression/function I could use? Any advice would be appreciated. Thank you!

thanks duane. that did the trick!