The CAS Registry Mumber 122631-53-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,2,6,3 and 1 respectively; the second part has 2 digits, 5 and 3 respectively. Calculate Digit Verification of CAS Registry Number 122631-53: (8*1)+(7*2)+(6*2)+(5*6)+(4*3)+(3*1)+(2*5)+(1*3)=92 92 % 10 = 2 So 122631-53-2 is a valid CAS Registry Number.