The CAS Registry Mumber 93516-20-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,3,5,1 and 6 respectively; the second part has 2 digits, 2 and 0 respectively. Calculate Digit Verification of CAS Registry Number 93516-20: (7*9)+(6*3)+(5*5)+(4*1)+(3*6)+(2*2)+(1*0)=132 132 % 10 = 2 So 93516-20-2 is a valid CAS Registry Number.