The CAS Registry Mumber 130534-35-9 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 4 respectively; the second part has 2 digits, 3 and 5 respectively. Calculate Digit Verification of CAS Registry Number 130534-35: (8*1)+(7*3)+(6*0)+(5*5)+(4*3)+(3*4)+(2*3)+(1*5)=89 89 % 10 = 9 So 130534-35-9 is a valid CAS Registry Number.