The CAS Registry Mumber 12712-90-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,2,7,1 and 2 respectively; the second part has 2 digits, 9 and 0 respectively. Calculate Digit Verification of CAS Registry Number 12712-90: (7*1)+(6*2)+(5*7)+(4*1)+(3*2)+(2*9)+(1*0)=82 82 % 10 = 2 So 12712-90-2 is a valid CAS Registry Number.