The CAS Registry Mumber 221072-60-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 2,2,1,0,7 and 2 respectively; the second part has 2 digits, 6 and 0 respectively. Calculate Digit Verification of CAS Registry Number 221072-60: (8*2)+(7*2)+(6*1)+(5*0)+(4*7)+(3*2)+(2*6)+(1*0)=82 82 % 10 = 2 So 221072-60-2 is a valid CAS Registry Number.