The CAS Registry Mumber 61289-19-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,1,2,8 and 9 respectively; the second part has 2 digits, 1 and 9 respectively. Calculate Digit Verification of CAS Registry Number 61289-19: (7*6)+(6*1)+(5*2)+(4*8)+(3*9)+(2*1)+(1*9)=128 128 % 10 = 8 So 61289-19-8 is a valid CAS Registry Number.