The CAS Registry Mumber 134387-69-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,4,3,8 and 7 respectively; the second part has 2 digits, 6 and 9 respectively. Calculate Digit Verification of CAS Registry Number 134387-69: (8*1)+(7*3)+(6*4)+(5*3)+(4*8)+(3*7)+(2*6)+(1*9)=142 142 % 10 = 2 So 134387-69-2 is a valid CAS Registry Number.