The CAS Registry Mumber 189253-51-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,8,9,2,5 and 3 respectively; the second part has 2 digits, 5 and 1 respectively. Calculate Digit Verification of CAS Registry Number 189253-51: (8*1)+(7*8)+(6*9)+(5*2)+(4*5)+(3*3)+(2*5)+(1*1)=168 168 % 10 = 8 So 189253-51-8 is a valid CAS Registry Number.