The CAS Registry Mumber 134695-91-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,4,6,9 and 5 respectively; the second part has 2 digits, 9 and 1 respectively. Calculate Digit Verification of CAS Registry Number 134695-91: (8*1)+(7*3)+(6*4)+(5*6)+(4*9)+(3*5)+(2*9)+(1*1)=153 153 % 10 = 3 So 134695-91-3 is a valid CAS Registry Number.