The CAS Registry Mumber 120163-91-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,0,1,6 and 3 respectively; the second part has 2 digits, 9 and 1 respectively. Calculate Digit Verification of CAS Registry Number 120163-91: (8*1)+(7*2)+(6*0)+(5*1)+(4*6)+(3*3)+(2*9)+(1*1)=79 79 % 10 = 9 So 120163-91-9 is a valid CAS Registry Number.