The CAS Registry Mumber 138299-08-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,8,2,9 and 9 respectively; the second part has 2 digits, 0 and 8 respectively. Calculate Digit Verification of CAS Registry Number 138299-08: (8*1)+(7*3)+(6*8)+(5*2)+(4*9)+(3*9)+(2*0)+(1*8)=158 158 % 10 = 8 So 138299-08-8 is a valid CAS Registry Number.