How To: Find and Remove Duplicates

Duplicate records inflate totals and spoil counts. The safe routine:

Find them: =COUNTIF($A$2:$A$9,A2)>1 flags repeats.
Check that they really are duplicates, not two people with the same name.
Remove: Data > Remove Duplicates on a copy of the data, or build a clean list with UNIQUE.

Counting how many are extra, rows - distinct values, tells you how big the problem is.

Exampleexcel

Quick check

Why copy the data before using Remove Duplicates?

The deletion cannot be checked or reversed laterIt makes Excel fasterIt is required by law

Your turn: write the code

Mark each row in B2:B5 with =COUNTIF(A2:A5,A2) so repeated names show a number above 1.

Finish the quick check (and any code exercise) to complete this lesson, or mark it done yourself.

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