The CAS Registry Mumber 1431138-09-8 includes 10 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 7 digits, 1,4,3,1,1,3 and 8 respectively; the second part has 2 digits, 0 and 9 respectively. Calculate Digit Verification of CAS Registry Number 1431138-09: (9*1)+(8*4)+(7*3)+(6*1)+(5*1)+(4*3)+(3*8)+(2*0)+(1*9)=118 118 % 10 = 8 So 1431138-09-8 is a valid CAS Registry Number.