checkbit[FREE] CAS
checkBIT 
CAS-format(PERLY) =: N_i ... N_3 "-" N_2 N_1 "-" N_0
=-= =-= =-= =-= 
mod10(i* N_i + ... + 3* N_3 + 2* N_2 + 1* N_1) =:  N_0 == checkbit

107-07-3 # beispiel aus CAS page
58-08-2 # cas of coffein
67-66-3 # Chloroform
7757-83-7 # Natriumsulfit
155378-37-3 # 2-Bromo-6-(heptyloxy)naphthalene
gen_cas_chkbit 0.2.1p 2021-12-05