The CAS Registry Mumber 52102-16-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,2,1,0 and 2 respectively; the second part has 2 digits, 1 and 6 respectively. Calculate Digit Verification of CAS Registry Number 52102-16: (7*5)+(6*2)+(5*1)+(4*0)+(3*2)+(2*1)+(1*6)=66 66 % 10 = 6 So 52102-16-6 is a valid CAS Registry Number.