The CAS Registry Mumber 79787-15-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,9,7,8 and 7 respectively; the second part has 2 digits, 1 and 5 respectively. Calculate Digit Verification of CAS Registry Number 79787-15: (7*7)+(6*9)+(5*7)+(4*8)+(3*7)+(2*1)+(1*5)=198 198 % 10 = 8 So 79787-15-8 is a valid CAS Registry Number.