The CAS Registry Mumber 5857-73-8 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 5,8,5 and 7 respectively; the second part has 2 digits, 7 and 3 respectively. Calculate Digit Verification of CAS Registry Number 5857-73: (6*5)+(5*8)+(4*5)+(3*7)+(2*7)+(1*3)=128 128 % 10 = 8 So 5857-73-8 is a valid CAS Registry Number.