SUMPRODUCT unique items

[Tufail]

hi,
how can i sum only once :

=IF($M6="","",SUMPRODUCT(($M$6:$M6=$M6)*($R$6:$R6)))

Col_M Col_R
20000 1000
21000 2000
20000 1000
22000 5000

thanks in advance...

 

[Bob Phillips]

=IF(OR($M6="",COUNTIF($M$6:$M6,M6)>1),"",SUMPRODUCT(($M$6:$M6=$M6)*($R$6:$R6)))

 

[Tufail]

thank you very much...

=IF(OR($M6="",COUNTIF($M$6:$M6,M6)>1),"",SUMPRODUCT(($M$6:$M6=$M6)*($R$6:$R6)))

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HTH

Bob