The CAS Registry Mumber 50304-38-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,0,3,0 and 4 respectively; the second part has 2 digits, 3 and 8 respectively. Calculate Digit Verification of CAS Registry Number 50304-38: (7*5)+(6*0)+(5*3)+(4*0)+(3*4)+(2*3)+(1*8)=76 76 % 10 = 6 So 50304-38-6 is a valid CAS Registry Number.