The CAS Registry Mumber 12011-61-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,2,0,1 and 1 respectively; the second part has 2 digits, 6 and 1 respectively. Calculate Digit Verification of CAS Registry Number 12011-61: (7*1)+(6*2)+(5*0)+(4*1)+(3*1)+(2*6)+(1*1)=39 39 % 10 = 9 So 12011-61-9 is a valid CAS Registry Number.