I need to calculate the IBAN from the bank no. and the account no. I know the algorithm, but one step is the MOD 97 operation of a 24 digit integer no. (here in Germany). I tried to use BigInteger and Decimal but got out of range. So the question would be: how could I calulate 500105170123456789131400 MOD 97? Or in the first place: how to create a variable that holds this BIG integer?

You must develop a MOD function in Navision that accepts strings.
You can develop such function, there are several available functions in other languages over the internet. You must convert it to C/AL

you just have to make sure that “sModulus” contains only numbers. Otherwise you get errors with the evaluate function.

I have seen a calculation in Navision for the “clé” (checksum) in the french RIB using modulus as well. And as they have long account numbers, there must be the same problem as yours. I should have a FR version somewhere. Will report later.