## banknote checksums

Euro banknotes
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### banknote checksums

I have a €20 note with serial number U02401890701. When I add up the digits I get a sum of 32 which is 3+2 = checksum for France. OK. The national code is "U" for France and it has a printing code of 'E" which is also France.

I have a €5 note with serial number X00025041809. When I add up the digits I get 29 which gives 2 + 9 = 11. With double digits supposed to use only first digit but that is 1 which is a "2". ???? The "X" is the national code for germany and the printing code is "P" which is also Germany. My question is why didn't I come up with a checksum of 2?
john1025
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Joined: 23 Mar 2013, 21:10

### Re: banknote checksums

X00025041809 => 29 => 2 + 9 = 11 => 1 +1 = 2 => 2 = checksum for Germany

Checksum is digital root which is calculated as long as only a single digit remains.

Best regards,
SME
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-- So Many Euros - The Software for Euro Coin Collectors --

So Many Euros

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Joined: 15 Dec 2008, 16:10
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### Re: banknote checksums

"<i>When I add up the digits I get 29 which gives 2 + 9 = 11</i>"
A 1 + 1 gives 2, which is code for Germany.

Description of checking validity of serial number is badly written.
It does not validate VA0436214792 note.

The simple description is simple:

Add digit within the serial number and add that sum to sum of ASCII codes for letters.
The sum divide by 9. If the remain is 0 the the serial number is OK.
in computer pseudo code:
if (SUM mod 9 == 0) print('serial number is OK');
Romek

### Re: banknote checksums

For the Europa series banknotes (the second series of euro banknotes) to calculate checksum and checkdigit treat the second letter as number. A = 11, B = 12, C = 13, D = 14, E = 15, F = 16 and so on.
For example UF9073937437
Checkdigit = 22+16+9+0+7+3+9+3+7+4+3+7 = 89, 8+9 = 17, 1+7 = 8
Checksum = 16+9+0+7+3+9+3+7+4+3+7 = 68, 6+8 = 14, 1+4 = 5 (as it must be for "U")
urbis