The CAS Registry Mumber 128231-14-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,8,2,3 and 1 respectively; the second part has 2 digits, 1 and 4 respectively. Calculate Digit Verification of CAS Registry Number 128231-14: (8*1)+(7*2)+(6*8)+(5*2)+(4*3)+(3*1)+(2*1)+(1*4)=101 101 % 10 = 1 So 128231-14-1 is a valid CAS Registry Number.