The CAS Registry Mumber 858616-39-4 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 8,5,8,6,1 and 6 respectively; the second part has 2 digits, 3 and 9 respectively. Calculate Digit Verification of CAS Registry Number 858616-39: (8*8)+(7*5)+(6*8)+(5*6)+(4*1)+(3*6)+(2*3)+(1*9)=214 214 % 10 = 4 So 858616-39-4 is a valid CAS Registry Number.