The CAS Registry Mumber 83767-36-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,3,7,6 and 7 respectively; the second part has 2 digits, 3 and 6 respectively. Calculate Digit Verification of CAS Registry Number 83767-36: (7*8)+(6*3)+(5*7)+(4*6)+(3*7)+(2*3)+(1*6)=166 166 % 10 = 6 So 83767-36-6 is a valid CAS Registry Number.