The CAS Registry Mumber 91477-34-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,1,4,7 and 7 respectively; the second part has 2 digits, 3 and 4 respectively. Calculate Digit Verification of CAS Registry Number 91477-34: (7*9)+(6*1)+(5*4)+(4*7)+(3*7)+(2*3)+(1*4)=148 148 % 10 = 8 So 91477-34-8 is a valid CAS Registry Number.