The CAS Registry Mumber 110808-08-7 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,0,8,0 and 8 respectively; the second part has 2 digits, 0 and 8 respectively. Calculate Digit Verification of CAS Registry Number 110808-08: (8*1)+(7*1)+(6*0)+(5*8)+(4*0)+(3*8)+(2*0)+(1*8)=87 87 % 10 = 7 So 110808-08-7 is a valid CAS Registry Number.