The CAS Registry Mumber 138252-35-4 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,8,2,5 and 2 respectively; the second part has 2 digits, 3 and 5 respectively. Calculate Digit Verification of CAS Registry Number 138252-35: (8*1)+(7*3)+(6*8)+(5*2)+(4*5)+(3*2)+(2*3)+(1*5)=124 124 % 10 = 4 So 138252-35-4 is a valid CAS Registry Number.