The CAS Registry Mumber 130539-17-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,0,5,3 and 9 respectively; the second part has 2 digits, 1 and 7 respectively. Calculate Digit Verification of CAS Registry Number 130539-17: (8*1)+(7*3)+(6*0)+(5*5)+(4*3)+(3*9)+(2*1)+(1*7)=102 102 % 10 = 2 So 130539-17-2 is a valid CAS Registry Number.