The CAS Registry Mumber 81126-45-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,1,1,2 and 6 respectively; the second part has 2 digits, 4 and 5 respectively. Calculate Digit Verification of CAS Registry Number 81126-45: (7*8)+(6*1)+(5*1)+(4*2)+(3*6)+(2*4)+(1*5)=106 106 % 10 = 6 So 81126-45-6 is a valid CAS Registry Number.