The CAS Registry Mumber 82769-79-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,2,7,6 and 9 respectively; the second part has 2 digits, 7 and 9 respectively. Calculate Digit Verification of CAS Registry Number 82769-79: (7*8)+(6*2)+(5*7)+(4*6)+(3*9)+(2*7)+(1*9)=177 177 % 10 = 7 So 82769-79-7 is a valid CAS Registry Number.