The CAS Registry Mumber 122221-02-7 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,2,2,2 and 1 respectively; the second part has 2 digits, 0 and 2 respectively. Calculate Digit Verification of CAS Registry Number 122221-02: (8*1)+(7*2)+(6*2)+(5*2)+(4*2)+(3*1)+(2*0)+(1*2)=57 57 % 10 = 7 So 122221-02-7 is a valid CAS Registry Number.