The CAS Registry Mumber 408504-93-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 4,0,8,5,0 and 4 respectively; the second part has 2 digits, 9 and 3 respectively. Calculate Digit Verification of CAS Registry Number 408504-93: (8*4)+(7*0)+(6*8)+(5*5)+(4*0)+(3*4)+(2*9)+(1*3)=138 138 % 10 = 8 So 408504-93-8 is a valid CAS Registry Number.