The CAS Registry Mumber 93677-99-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,3,6,7 and 7 respectively; the second part has 2 digits, 9 and 9 respectively. Calculate Digit Verification of CAS Registry Number 93677-99: (7*9)+(6*3)+(5*6)+(4*7)+(3*7)+(2*9)+(1*9)=187 187 % 10 = 7 So 93677-99-7 is a valid CAS Registry Number.