The CAS Registry Mumber 181636-95-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,8,1,6,3 and 6 respectively; the second part has 2 digits, 9 and 5 respectively. Calculate Digit Verification of CAS Registry Number 181636-95: (8*1)+(7*8)+(6*1)+(5*6)+(4*3)+(3*6)+(2*9)+(1*5)=153 153 % 10 = 3 So 181636-95-3 is a valid CAS Registry Number.