The CAS Registry Mumber 123027-50-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,3,0,2 and 7 respectively; the second part has 2 digits, 5 and 0 respectively. Calculate Digit Verification of CAS Registry Number 123027-50: (8*1)+(7*2)+(6*3)+(5*0)+(4*2)+(3*7)+(2*5)+(1*0)=79 79 % 10 = 9 So 123027-50-9 is a valid CAS Registry Number.