The CAS Registry Mumber 57456-74-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,7,4,5 and 6 respectively; the second part has 2 digits, 7 and 4 respectively. Calculate Digit Verification of CAS Registry Number 57456-74: (7*5)+(6*7)+(5*4)+(4*5)+(3*6)+(2*7)+(1*4)=153 153 % 10 = 3 So 57456-74-3 is a valid CAS Registry Number.