The CAS Registry Mumber 116673-97-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,6,6,7 and 3 respectively; the second part has 2 digits, 9 and 7 respectively. Calculate Digit Verification of CAS Registry Number 116673-97: (8*1)+(7*1)+(6*6)+(5*6)+(4*7)+(3*3)+(2*9)+(1*7)=143 143 % 10 = 3 So 116673-97-3 is a valid CAS Registry Number.