Two suggestions to improve on the efficiency of the check computations in the banking system in Belgium (Q1119172)

Choosing \(m=97\) as modulus for the computation of the check digits in an account number of a Belgian bank account, it was assumed that m had to be selected from the set of primes. We show that this restrictive assumption is incorrect by introducing \(m=93\) as a more efficient modulus than the current \(m=97\). The advantage of using \(m=93\) appears in the capacity of detecting two altered digits. We also present a slight modification of the check system, yet more reducing the probability of an undetectable error pattern. The paper may be of practical interest for bankings in those countries where a national standard structure of account numbers does not yet exist, but where its establishment is given serious consideration to.