The CAS Registry Mumber 4945-58-8 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,9,4 and 5 respectively; the second part has 2 digits, 5 and 8 respectively. Calculate Digit Verification of CAS Registry Number 4945-58: (6*4)+(5*9)+(4*4)+(3*5)+(2*5)+(1*8)=118 118 % 10 = 8 So 4945-58-8 is a valid CAS Registry Number.