The CAS Registry Mumber 136317-06-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,6,3,1 and 7 respectively; the second part has 2 digits, 0 and 6 respectively. Calculate Digit Verification of CAS Registry Number 136317-06: (8*1)+(7*3)+(6*6)+(5*3)+(4*1)+(3*7)+(2*0)+(1*6)=111 111 % 10 = 1 So 136317-06-1 is a valid CAS Registry Number.