The CAS Registry Mumber 122503-12-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,2,5,0 and 3 respectively; the second part has 2 digits, 1 and 2 respectively. Calculate Digit Verification of CAS Registry Number 122503-12: (8*1)+(7*2)+(6*2)+(5*5)+(4*0)+(3*3)+(2*1)+(1*2)=72 72 % 10 = 2 So 122503-12-2 is a valid CAS Registry Number.