The CAS Registry Mumber 184034-17-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,8,4,0,3 and 4 respectively; the second part has 2 digits, 1 and 7 respectively. Calculate Digit Verification of CAS Registry Number 184034-17: (8*1)+(7*8)+(6*4)+(5*0)+(4*3)+(3*4)+(2*1)+(1*7)=121 121 % 10 = 1 So 184034-17-1 is a valid CAS Registry Number.