The CAS Registry Mumber 79968-08-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,9,9,6 and 8 respectively; the second part has 2 digits, 0 and 8 respectively. Calculate Digit Verification of CAS Registry Number 79968-08: (7*7)+(6*9)+(5*9)+(4*6)+(3*8)+(2*0)+(1*8)=204 204 % 10 = 4 So 79968-08-4 is a valid CAS Registry Number.