The steps to what I am trying to do are as follows:
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User enters 12 digit UPC/UCC (aka Barcode) code into form on web site. 
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Last digit (the check digit) is dropped from the number entered. 
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This formula is run on the remaining 11 digits: http://www.uc-council.org/ean_ucc_s.../cdc.html#UCC12 
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the result is compared to the dropped digit. 
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If equal, echo “Hooray!” because I have bashed my head over this for days; 
Can anyone provide any tips, or point me to something like this that may already exist? I have found plenty of check digit calculators, but no validators.
Thanks!
