The CAS Registry Mumber 102073-87-0 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,2,0,7 and 3 respectively; the second part has 2 digits, 8 and 7 respectively. Calculate Digit Verification of CAS Registry Number 102073-87: (8*1)+(7*0)+(6*2)+(5*0)+(4*7)+(3*3)+(2*8)+(1*7)=80 80 % 10 = 0 So 102073-87-0 is a valid CAS Registry Number.