The CAS Registry Mumber 85452-28-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,5,4,5 and 2 respectively; the second part has 2 digits, 2 and 8 respectively. Calculate Digit Verification of CAS Registry Number 85452-28: (7*8)+(6*5)+(5*4)+(4*5)+(3*2)+(2*2)+(1*8)=144 144 % 10 = 4 So 85452-28-4 is a valid CAS Registry Number.