The CAS Registry Mumber 79677-65-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,9,6,7 and 7 respectively; the second part has 2 digits, 6 and 5 respectively. Calculate Digit Verification of CAS Registry Number 79677-65: (7*7)+(6*9)+(5*6)+(4*7)+(3*7)+(2*6)+(1*5)=199 199 % 10 = 9 So 79677-65-9 is a valid CAS Registry Number.