The CAS Registry Mumber 191355-96-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,9,1,3,5 and 5 respectively; the second part has 2 digits, 9 and 6 respectively. Calculate Digit Verification of CAS Registry Number 191355-96: (8*1)+(7*9)+(6*1)+(5*3)+(4*5)+(3*5)+(2*9)+(1*6)=151 151 % 10 = 1 So 191355-96-1 is a valid CAS Registry Number.