The CAS Registry Mumber 4974-97-4 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,9,7 and 4 respectively; the second part has 2 digits, 9 and 7 respectively. Calculate Digit Verification of CAS Registry Number 4974-97: (6*4)+(5*9)+(4*7)+(3*4)+(2*9)+(1*7)=134 134 % 10 = 4 So 4974-97-4 is a valid CAS Registry Number.