The CAS Registry Mumber 76662-79-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,6,6,6 and 2 respectively; the second part has 2 digits, 7 and 9 respectively. Calculate Digit Verification of CAS Registry Number 76662-79: (7*7)+(6*6)+(5*6)+(4*6)+(3*2)+(2*7)+(1*9)=168 168 % 10 = 8 So 76662-79-8 is a valid CAS Registry Number.