The CAS Registry Mumber 73284-92-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,3,2,8 and 4 respectively; the second part has 2 digits, 9 and 2 respectively. Calculate Digit Verification of CAS Registry Number 73284-92: (7*7)+(6*3)+(5*2)+(4*8)+(3*4)+(2*9)+(1*2)=141 141 % 10 = 1 So 73284-92-1 is a valid CAS Registry Number.