The CAS Registry Mumber 79388-65-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,9,3,8 and 8 respectively; the second part has 2 digits, 6 and 5 respectively. Calculate Digit Verification of CAS Registry Number 79388-65: (7*7)+(6*9)+(5*3)+(4*8)+(3*8)+(2*6)+(1*5)=191 191 % 10 = 1 So 79388-65-1 is a valid CAS Registry Number.