The CAS Registry Mumber 118202-61-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,8,2,0 and 2 respectively; the second part has 2 digits, 6 and 1 respectively. Calculate Digit Verification of CAS Registry Number 118202-61: (8*1)+(7*1)+(6*8)+(5*2)+(4*0)+(3*2)+(2*6)+(1*1)=92 92 % 10 = 2 So 118202-61-2 is a valid CAS Registry Number.