The CAS Registry Mumber 195189-72-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,9,5,1,8 and 9 respectively; the second part has 2 digits, 7 and 2 respectively. Calculate Digit Verification of CAS Registry Number 195189-72: (8*1)+(7*9)+(6*5)+(5*1)+(4*8)+(3*9)+(2*7)+(1*2)=181 181 % 10 = 1 So 195189-72-1 is a valid CAS Registry Number.