The CAS Registry Mumber 104329-83-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,4,3,2 and 9 respectively; the second part has 2 digits, 8 and 3 respectively. Calculate Digit Verification of CAS Registry Number 104329-83: (8*1)+(7*0)+(6*4)+(5*3)+(4*2)+(3*9)+(2*8)+(1*3)=101 101 % 10 = 1 So 104329-83-1 is a valid CAS Registry Number.