The CAS Registry Mumber 74454-12-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,4,4,5 and 4 respectively; the second part has 2 digits, 1 and 2 respectively. Calculate Digit Verification of CAS Registry Number 74454-12: (7*7)+(6*4)+(5*4)+(4*5)+(3*4)+(2*1)+(1*2)=129 129 % 10 = 9 So 74454-12-9 is a valid CAS Registry Number.