The CAS Registry Mumber 184708-65-4 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,8,4,7,0 and 8 respectively; the second part has 2 digits, 6 and 5 respectively. Calculate Digit Verification of CAS Registry Number 184708-65: (8*1)+(7*8)+(6*4)+(5*7)+(4*0)+(3*8)+(2*6)+(1*5)=164 164 % 10 = 4 So 184708-65-4 is a valid CAS Registry Number.