The CAS Registry Mumber 138769-02-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,8,7,6 and 9 respectively; the second part has 2 digits, 0 and 2 respectively. Calculate Digit Verification of CAS Registry Number 138769-02: (8*1)+(7*3)+(6*8)+(5*7)+(4*6)+(3*9)+(2*0)+(1*2)=165 165 % 10 = 5 So 138769-02-5 is a valid CAS Registry Number.