The CAS Registry Mumber 4198-97-4 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,1,9 and 8 respectively; the second part has 2 digits, 9 and 7 respectively. Calculate Digit Verification of CAS Registry Number 4198-97: (6*4)+(5*1)+(4*9)+(3*8)+(2*9)+(1*7)=114 114 % 10 = 4 So 4198-97-4 is a valid CAS Registry Number.