The CAS Registry Mumber 58851-58-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,8,8,5 and 1 respectively; the second part has 2 digits, 5 and 8 respectively. Calculate Digit Verification of CAS Registry Number 58851-58: (7*5)+(6*8)+(5*8)+(4*5)+(3*1)+(2*5)+(1*8)=164 164 % 10 = 4 So 58851-58-4 is a valid CAS Registry Number.