The CAS Registry Mumber 89680-84-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,9,6,8 and 0 respectively; the second part has 2 digits, 8 and 4 respectively. Calculate Digit Verification of CAS Registry Number 89680-84: (7*8)+(6*9)+(5*6)+(4*8)+(3*0)+(2*8)+(1*4)=192 192 % 10 = 2 So 89680-84-2 is a valid CAS Registry Number.