The CAS Registry Mumber 136860-13-4 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 0 respectively; the second part has 2 digits, 1 and 3 respectively. Calculate Digit Verification of CAS Registry Number 136860-13: (8*1)+(7*3)+(6*6)+(5*8)+(4*6)+(3*0)+(2*1)+(1*3)=134 134 % 10 = 4 So 136860-13-4 is a valid CAS Registry Number.