The CAS Registry Mumber 102339-76-4 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,2,3,3 and 9 respectively; the second part has 2 digits, 7 and 6 respectively. Calculate Digit Verification of CAS Registry Number 102339-76: (8*1)+(7*0)+(6*2)+(5*3)+(4*3)+(3*9)+(2*7)+(1*6)=94 94 % 10 = 4 So 102339-76-4 is a valid CAS Registry Number.