The CAS Registry Mumber 73870-97-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,3,8,7 and 0 respectively; the second part has 2 digits, 9 and 7 respectively. Calculate Digit Verification of CAS Registry Number 73870-97: (7*7)+(6*3)+(5*8)+(4*7)+(3*0)+(2*9)+(1*7)=160 160 % 10 = 0 So 73870-97-0 is a valid CAS Registry Number.