The CAS Registry Mumber 116206-91-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,6,2,0 and 6 respectively; the second part has 2 digits, 9 and 1 respectively. Calculate Digit Verification of CAS Registry Number 116206-91: (8*1)+(7*1)+(6*6)+(5*2)+(4*0)+(3*6)+(2*9)+(1*1)=98 98 % 10 = 8 So 116206-91-8 is a valid CAS Registry Number.