The CAS Registry Mumber 128926-49-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,8,9,2 and 6 respectively; the second part has 2 digits, 4 and 9 respectively. Calculate Digit Verification of CAS Registry Number 128926-49: (8*1)+(7*2)+(6*8)+(5*9)+(4*2)+(3*6)+(2*4)+(1*9)=158 158 % 10 = 8 So 128926-49-8 is a valid CAS Registry Number.