The CAS Registry Mumber 136707-38-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,6,7,0 and 7 respectively; the second part has 2 digits, 3 and 8 respectively. Calculate Digit Verification of CAS Registry Number 136707-38: (8*1)+(7*3)+(6*6)+(5*7)+(4*0)+(3*7)+(2*3)+(1*8)=135 135 % 10 = 5 So 136707-38-5 is a valid CAS Registry Number.