The CAS Registry Mumber 82236-42-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,2,2,3 and 6 respectively; the second part has 2 digits, 4 and 2 respectively. Calculate Digit Verification of CAS Registry Number 82236-42: (7*8)+(6*2)+(5*2)+(4*3)+(3*6)+(2*4)+(1*2)=118 118 % 10 = 8 So 82236-42-8 is a valid CAS Registry Number.