The CAS Registry Mumber 4425-74-5 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,4,2 and 5 respectively; the second part has 2 digits, 7 and 4 respectively. Calculate Digit Verification of CAS Registry Number 4425-74: (6*4)+(5*4)+(4*2)+(3*5)+(2*7)+(1*4)=85 85 % 10 = 5 So 4425-74-5 is a valid CAS Registry Number.