The CAS Registry Mumber 858371-92-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 8,5,8,3,7 and 1 respectively; the second part has 2 digits, 9 and 2 respectively. Calculate Digit Verification of CAS Registry Number 858371-92: (8*8)+(7*5)+(6*8)+(5*3)+(4*7)+(3*1)+(2*9)+(1*2)=213 213 % 10 = 3 So 858371-92-3 is a valid CAS Registry Number.