The CAS Registry Mumber 116826-69-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,6,8,2 and 6 respectively; the second part has 2 digits, 6 and 9 respectively. Calculate Digit Verification of CAS Registry Number 116826-69: (8*1)+(7*1)+(6*6)+(5*8)+(4*2)+(3*6)+(2*6)+(1*9)=138 138 % 10 = 8 So 116826-69-8 is a valid CAS Registry Number.