The CAS Registry Mumber 126712-11-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,6,7,1 and 2 respectively; the second part has 2 digits, 1 and 1 respectively. Calculate Digit Verification of CAS Registry Number 126712-11: (8*1)+(7*2)+(6*6)+(5*7)+(4*1)+(3*2)+(2*1)+(1*1)=106 106 % 10 = 6 So 126712-11-6 is a valid CAS Registry Number.