The CAS Registry Mumber 120919-03-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,0,9,1 and 9 respectively; the second part has 2 digits, 0 and 3 respectively. Calculate Digit Verification of CAS Registry Number 120919-03: (8*1)+(7*2)+(6*0)+(5*9)+(4*1)+(3*9)+(2*0)+(1*3)=101 101 % 10 = 1 So 120919-03-1 is a valid CAS Registry Number.