count the number of times each string appears in a column and make a summary column

If ive got a column with 50 alpha-numeric entries where a few of them appear more than once in the column (and the rest appear only once), how do i make a count of how many times each entry occurs with a summary column with the details of the count. I wanted to try this in the attached file for column B tilted 'Secondary Id''s . In the attached file there is only 20 -30 entries but on another day this may be thousands.

basically, I need to establish how many non-unique Secondary Id's that i have.

Some things are simpler with builtin Excel tools, I'd use a Pivot Table to give you a quick unique count.

Watch this Tutorial.

Also a simple countif does the same job.

In F2 and copy down.

=COUNTIF($B$2:$B$27,B2)

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