The CAS Registry Mumber 54493-49-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,4,4,9 and 3 respectively; the second part has 2 digits, 4 and 9 respectively. Calculate Digit Verification of CAS Registry Number 54493-49: (7*5)+(6*4)+(5*4)+(4*9)+(3*3)+(2*4)+(1*9)=141 141 % 10 = 1 So 54493-49-1 is a valid CAS Registry Number.