The CAS Registry Mumber 155473-74-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,5,5,4,7 and 3 respectively; the second part has 2 digits, 7 and 4 respectively. Calculate Digit Verification of CAS Registry Number 155473-74: (8*1)+(7*5)+(6*5)+(5*4)+(4*7)+(3*3)+(2*7)+(1*4)=148 148 % 10 = 8 So 155473-74-8 is a valid CAS Registry Number.