The CAS Registry Mumber 98571-16-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,8,5,7 and 1 respectively; the second part has 2 digits, 1 and 6 respectively. Calculate Digit Verification of CAS Registry Number 98571-16: (7*9)+(6*8)+(5*5)+(4*7)+(3*1)+(2*1)+(1*6)=175 175 % 10 = 5 So 98571-16-5 is a valid CAS Registry Number.