The CAS Registry Mumber 130121-11-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,0,1,2 and 1 respectively; the second part has 2 digits, 1 and 1 respectively. Calculate Digit Verification of CAS Registry Number 130121-11: (8*1)+(7*3)+(6*0)+(5*1)+(4*2)+(3*1)+(2*1)+(1*1)=48 48 % 10 = 8 So 130121-11-8 is a valid CAS Registry Number.