The CAS Registry Mumber 116826-71-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,6,8,2 and 6 respectively; the second part has 2 digits, 7 and 1 respectively. Calculate Digit Verification of CAS Registry Number 116826-71: (8*1)+(7*1)+(6*6)+(5*8)+(4*2)+(3*6)+(2*7)+(1*1)=132 132 % 10 = 2 So 116826-71-2 is a valid CAS Registry Number.