The CAS Registry Mumber 12226-25-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,2,2,2 and 6 respectively; the second part has 2 digits, 2 and 5 respectively. Calculate Digit Verification of CAS Registry Number 12226-25: (7*1)+(6*2)+(5*2)+(4*2)+(3*6)+(2*2)+(1*5)=64 64 % 10 = 4 So 12226-25-4 is a valid CAS Registry Number.