The CAS Registry Mumber 12604-57-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,2,6,0 and 4 respectively; the second part has 2 digits, 5 and 7 respectively. Calculate Digit Verification of CAS Registry Number 12604-57: (7*1)+(6*2)+(5*6)+(4*0)+(3*4)+(2*5)+(1*7)=78 78 % 10 = 8 So 12604-57-8 is a valid CAS Registry Number.