The CAS Registry Mumber 4657-41-4 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,6,5 and 7 respectively; the second part has 2 digits, 4 and 1 respectively. Calculate Digit Verification of CAS Registry Number 4657-41: (6*4)+(5*6)+(4*5)+(3*7)+(2*4)+(1*1)=104 104 % 10 = 4 So 4657-41-4 is a valid CAS Registry Number.