The CAS Registry Mumber 170080-38-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,7,0,0,8 and 0 respectively; the second part has 2 digits, 3 and 8 respectively. Calculate Digit Verification of CAS Registry Number 170080-38: (8*1)+(7*7)+(6*0)+(5*0)+(4*8)+(3*0)+(2*3)+(1*8)=103 103 % 10 = 3 So 170080-38-3 is a valid CAS Registry Number.