The CAS Registry Mumber 385434-58-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 3,8,5,4,3 and 4 respectively; the second part has 2 digits, 5 and 8 respectively. Calculate Digit Verification of CAS Registry Number 385434-58: (8*3)+(7*8)+(6*5)+(5*4)+(4*3)+(3*4)+(2*5)+(1*8)=172 172 % 10 = 2 So 385434-58-2 is a valid CAS Registry Number.