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Checksum calculation formula
Can't find any examples) of EC# that would validate using the checksum digit calculation formula provided. Where this formula comes from? Shevelevs (talk) 16:03, 2 February 2008 (UTC)[reply]

Three EC numbers are given in the article. I added the names that go with them so that it would be clearer that they can be used as examples. That the formula works can be verified by entering these numbers in the ESIS web site (it's listed in the External links). On changing the check digit, I got the message, "EC# Not Found in ESIS." This appears to validate the formula. However, I find no official documentation on the web of the check-digit formula for EC numbers. (It is documented by the European Commission for use in "index numbers" of chemicals.) --Christopher King (talk) 20:32, 7 February 2009 (UTC)[reply]

In other words, you admit that the formula quoted is incorrect. Nobody is doubting that the last digit is a checksum, merely the formula used to calculate it. The current formula doesn't agree with the quoted EC numbers and, so I'm removing it. If you wish to try to figure out the correct formula, here are the first ten entries in the EINECS:

Physchim62 (talk) 20:58, 7 February 2009 (UTC)[reply]

But the formula does work. I don't see the problem. However, if two of you can't make the formula work, then an example is needed. I'll revert your removal and add an example calculation.--Christopher King (talk) 17:31, 8 February 2009 (UTC)[reply]

I stumbled over some EC numbers used, but according to checksum formula are not valid:

417-650-1 : (cas: 88128-57-8) : 1,3-Dioxane,2-(3-chloropropyl)-2,5,5-trimethyl

415-180-1 : (cas: 773058-82-5) : mono-2-[2-(4-dibenzo[b,f][1,4]thiazepin-11-yl)piperazinium-1-yl]ethoxy)ethanol trans-butenedioate

424-550-1 : (cas: 84245-12-5) : N-[6,9-dihydro-9-[[2-hydroxy-1-(hydroxymethyl)ethoxy]methyl]-6-oxo-1H-purin-2-yl]acetamide

Any idea's whats happening here? — Preceding unsigned comment added by 213.69.137.195 (talk) 07:39, 22 March 2012 (UTC)[reply]

Another example:

431-060-1 : (cas: 153719) : N-Nitro-N-(3-methyl-3,6-dihydro-2H-1,3,5-oxadiazin-4-yl)amine

and: 416-840-1 418-140-1 419-590-1 423-740-1 424-090-1 426-700-1 427-900-1 430-250-1 432-260-1 436-030-1 — Preceding unsigned comment added by 93.134.149.15 (talk) 13:44, 11 October 2013 (UTC)[reply]

These are all cases where the checksum = 10. — Preceding unsigned comment added by 93.134.149.15 (talk) 12:42, 11 October 2013 (UTC)[reply]