The CAS Registry Mumber 84066-36-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,4,0,6 and 6 respectively; the second part has 2 digits, 3 and 6 respectively. Calculate Digit Verification of CAS Registry Number 84066-36: (7*8)+(6*4)+(5*0)+(4*6)+(3*6)+(2*3)+(1*6)=134 134 % 10 = 4 So 84066-36-4 is a valid CAS Registry Number.