The CAS Registry Mumber 98413-34-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,8,4,1 and 3 respectively; the second part has 2 digits, 3 and 4 respectively. Calculate Digit Verification of CAS Registry Number 98413-34: (7*9)+(6*8)+(5*4)+(4*1)+(3*3)+(2*3)+(1*4)=154 154 % 10 = 4 So 98413-34-4 is a valid CAS Registry Number.