The CAS Registry Mumber 97387-82-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,7,3,8 and 7 respectively; the second part has 2 digits, 8 and 2 respectively. Calculate Digit Verification of CAS Registry Number 97387-82: (7*9)+(6*7)+(5*3)+(4*8)+(3*7)+(2*8)+(1*2)=191 191 % 10 = 1 So 97387-82-1 is a valid CAS Registry Number.