The CAS Registry Mumber 74454-23-2 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, 2 and 3 respectively. Calculate Digit Verification of CAS Registry Number 74454-23: (7*7)+(6*4)+(5*4)+(4*5)+(3*4)+(2*2)+(1*3)=132 132 % 10 = 2 So 74454-23-2 is a valid CAS Registry Number.