The CAS Registry Mumber 4451-85-8 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,4,5 and 1 respectively; the second part has 2 digits, 8 and 5 respectively. Calculate Digit Verification of CAS Registry Number 4451-85: (6*4)+(5*4)+(4*5)+(3*1)+(2*8)+(1*5)=88 88 % 10 = 8 So 4451-85-8 is a valid CAS Registry Number.