The CAS Registry Mumber 129190-81-4 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,9,1,9 and 0 respectively; the second part has 2 digits, 8 and 1 respectively. Calculate Digit Verification of CAS Registry Number 129190-81: (8*1)+(7*2)+(6*9)+(5*1)+(4*9)+(3*0)+(2*8)+(1*1)=134 134 % 10 = 4 So 129190-81-4 is a valid CAS Registry Number.