The CAS Registry Mumber 63186-18-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,3,1,8 and 6 respectively; the second part has 2 digits, 1 and 8 respectively. Calculate Digit Verification of CAS Registry Number 63186-18: (7*6)+(6*3)+(5*1)+(4*8)+(3*6)+(2*1)+(1*8)=125 125 % 10 = 5 So 63186-18-5 is a valid CAS Registry Number.