The CAS Registry Mumber 80284-16-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,0,2,8 and 4 respectively; the second part has 2 digits, 1 and 6 respectively. Calculate Digit Verification of CAS Registry Number 80284-16: (7*8)+(6*0)+(5*2)+(4*8)+(3*4)+(2*1)+(1*6)=118 118 % 10 = 8 So 80284-16-8 is a valid CAS Registry Number.