The CAS Registry Mumber 85198-34-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,5,1,9 and 8 respectively; the second part has 2 digits, 3 and 4 respectively. Calculate Digit Verification of CAS Registry Number 85198-34: (7*8)+(6*5)+(5*1)+(4*9)+(3*8)+(2*3)+(1*4)=161 161 % 10 = 1 So 85198-34-1 is a valid CAS Registry Number.