The CAS Registry Mumber 127812-05-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,7,8,1 and 2 respectively; the second part has 2 digits, 0 and 5 respectively. Calculate Digit Verification of CAS Registry Number 127812-05: (8*1)+(7*2)+(6*7)+(5*8)+(4*1)+(3*2)+(2*0)+(1*5)=119 119 % 10 = 9 So 127812-05-9 is a valid CAS Registry Number.