The CAS Registry Mumber 289066-04-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 2,8,9,0,6 and 6 respectively; the second part has 2 digits, 0 and 4 respectively. Calculate Digit Verification of CAS Registry Number 289066-04: (8*2)+(7*8)+(6*9)+(5*0)+(4*6)+(3*6)+(2*0)+(1*4)=172 172 % 10 = 2 So 289066-04-2 is a valid CAS Registry Number.