Source link:
http://www.av1611.org/666/barcode.html
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Two people at another forum told me that the only "666" they could see was the 3 added to the picture...

Thats why I will post a little more about this:
Notice. The beginning and ending guard bars are "bar-space-bar" or "101" (the B in the above table). The middle guard bar is "space-bar-space-bar-space" or "01010" (the M in the above table). The number six is "1010000" (the 6 in the above table). Remember, technically a barcode number consists of seven units. The beginning and ending guard bars are only three units, and middle guard bar is only five units.
So, technically, from a computer's perspective the number "666" is NOT in the UPC barcode.
But. . .
Look again. . . All three guard bars contain the pattern "bar-space-bar" or "101". There is only ONE number, in TWENTY numbers (remember right and left numbers have different patterns) that contains the "101" pattern and that number is the right code SIX. Not the number one, or two, or three, etc. — but ONLY the right code SIX. I do seem to remember something about a mark on the RIGHT hand (Rev. 13:16).
Technically, from a computer's perspective the number "666" is NOT in the UPC barcode. . . but from a human's perspective : YES, the "appearance" of 666 is there!
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PaCmAns NOTE: When you scan a barcode, the checksum that will make is possible for the computer to go "BEEP" insted of "BEEEEEEEEEEEPPPPPPPP" is the 3 x double bars running all the way to the bottom - And the numbers are 6 - 6 - 6.
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