Calculation of a modulo 10 control key

[loulou2522]

I am looking for an example that allows the calculation of a key from a modulo 10 example.
210000000003139471430009017
the result is 7 (position 27 of the figure)
Thank you in advance for helping me

[wilbert]

What type of numbers do you have ?
Internal formats PB supports like Quad or Double aren't suitable for this kind of large integer values.
If they are strings, you can just take the last character.

[NicTheQuick]

If your numbers are already represented as decimal strings then just extract the last digit and there you go.

In all other cases: Please give us more information.

[BarryG]

just extract the last digit

Surely that's not always going to be the case? We're talking key calculations here. The 7 in the original post was just an example for that specific calculation, no?

[NicTheQuick]

What is a key calculation? Are we talking about private and public keys or signatures? I don't get it.

[Kurzer]

Nic, I suspect that he means a so called "check digit calculation" (in german "Prüfziffernberechnung").

@loulou2522:

This is a modulo 10 checksum calculation with weighting 2.

Code: Select all

Procedure.s CalcChecksum(sNumber.s)
	Protected.i i, iDigit, iSum, iLen
	
	iLen = Len(sNumber)
		
		iSum = 0
		For i = 1 To iLen
			iDigit = Val(Mid(sNumber, i, 1))
			If i % 2 = 0 : iDigit * 2 : EndIf
			iSum + iDigit
		Next i
		ProcedureReturn Str((10 - iSum % 10) %10)
EndProcedure

Debug CalcChecksum("21000000000313947143000901")

You can get information about the check digit calculation methods here:
https://www.activebarcode.com/codes/che ... ulo10.html

Markus

[Mohawk70]

Nic, I suspect that he means a so called "check digit calculation" (in german "Prüfziffernberechnung").

@loulou2522:

This is a modulo 10 checksum calculation with weighting 2.

Code: Select all

Procedure.s CalcChecksum(sNumber.s)
	Protected.i i, iDigit, iSum, iLen
	
	iLen = Len(sNumber)
		
		iSum = 0
		For i = 1 To iLen
			iDigit = Val(Mid(sNumber, i, 1))
			If i % 2 = 0 : iDigit * 2 : EndIf
			iSum + iDigit
		Next i
		ProcedureReturn Str((10 - iSum % 10) %10)
EndProcedure

Debug CalcChecksum("21000000000313947143000901")

You can get information about the check digit calculation methods here:
https://www.activebarcode.com/codes/che ... ulo10.html

Markus

Google "Luhn Formula" or "Luhn calculation"