What formula would show me I already entered an invoice number once before?

  • Thread starter Thread starter Marvin Hlavac
  • Start date Start date
M

Marvin Hlavac

Hi All,

In column A I enter invoice numbers. Occasionally the same invoice number is
entered by a mistake. How to avoid that? Perhaps in column B a warning would
be displayed beside the invoice number that was entered second time. What
formula could I use?
 
Marvin, here is one way, will check for duplicates in A1:A10, change as
needed
=IF(SUMPRODUCT((COUNTIF(A1:A10,A1:A10)>1)+0)>1,"Duplicates exist","")

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Paul B
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Using Excel 2000 & 97
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Hi Paul,

Marvin, here is one way, will check for duplicates in A1:A10, change as
needed
=IF(SUMPRODUCT((COUNTIF(A1:A10,A1:A10)>1)+0)>1,"Duplicates exist","")
Click to expand...


It works and it is exactly what I needed. Thanks a million.
 
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