The CAS Registry Mumber 77085-99-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,7,0,8 and 5 respectively; the second part has 2 digits, 9 and 9 respectively. Calculate Digit Verification of CAS Registry Number 77085-99: (7*7)+(6*7)+(5*0)+(4*8)+(3*5)+(2*9)+(1*9)=165 165 % 10 = 5 So 77085-99-5 is a valid CAS Registry Number.