The CAS Registry Mumber 469-91-0 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 4,6 and 9 respectively; the second part has 2 digits, 9 and 1 respectively. Calculate Digit Verification of CAS Registry Number 469-91: (5*4)+(4*6)+(3*9)+(2*9)+(1*1)=90 90 % 10 = 0 So 469-91-0 is a valid CAS Registry Number.