The CAS Registry Mumber 136863-38-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,6,8,6 and 3 respectively; the second part has 2 digits, 3 and 8 respectively. Calculate Digit Verification of CAS Registry Number 136863-38: (8*1)+(7*3)+(6*6)+(5*8)+(4*6)+(3*3)+(2*3)+(1*8)=152 152 % 10 = 2 So 136863-38-2 is a valid CAS Registry Number.