The CAS Registry Mumber 128915-36-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,8,9,1 and 5 respectively; the second part has 2 digits, 3 and 6 respectively. Calculate Digit Verification of CAS Registry Number 128915-36: (8*1)+(7*2)+(6*8)+(5*9)+(4*1)+(3*5)+(2*3)+(1*6)=146 146 % 10 = 6 So 128915-36-6 is a valid CAS Registry Number.