The CAS Registry Mumber 57604-45-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,7,6,0 and 4 respectively; the second part has 2 digits, 4 and 5 respectively. Calculate Digit Verification of CAS Registry Number 57604-45: (7*5)+(6*7)+(5*6)+(4*0)+(3*4)+(2*4)+(1*5)=132 132 % 10 = 2 So 57604-45-2 is a valid CAS Registry Number.