The CAS Registry Mumber 85107-66-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,5,1,0 and 7 respectively; the second part has 2 digits, 6 and 6 respectively. Calculate Digit Verification of CAS Registry Number 85107-66: (7*8)+(6*5)+(5*1)+(4*0)+(3*7)+(2*6)+(1*6)=130 130 % 10 = 0 So 85107-66-0 is a valid CAS Registry Number.