The CAS Registry Mumber 779-96-4 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 7,7 and 9 respectively; the second part has 2 digits, 9 and 6 respectively. Calculate Digit Verification of CAS Registry Number 779-96: (5*7)+(4*7)+(3*9)+(2*9)+(1*6)=114 114 % 10 = 4 So 779-96-4 is a valid CAS Registry Number.