The CAS Registry Mumber 120031-61-0 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,0,0,3 and 1 respectively; the second part has 2 digits, 6 and 1 respectively. Calculate Digit Verification of CAS Registry Number 120031-61: (8*1)+(7*2)+(6*0)+(5*0)+(4*3)+(3*1)+(2*6)+(1*1)=50 50 % 10 = 0 So 120031-61-0 is a valid CAS Registry Number.