The CAS Registry Mumber 90691-46-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,0,6,9 and 1 respectively; the second part has 2 digits, 4 and 6 respectively. Calculate Digit Verification of CAS Registry Number 90691-46: (7*9)+(6*0)+(5*6)+(4*9)+(3*1)+(2*4)+(1*6)=146 146 % 10 = 6 So 90691-46-6 is a valid CAS Registry Number.