The CAS Registry Mumber 82855-13-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,2,8,5 and 5 respectively; the second part has 2 digits, 1 and 3 respectively. Calculate Digit Verification of CAS Registry Number 82855-13: (7*8)+(6*2)+(5*8)+(4*5)+(3*5)+(2*1)+(1*3)=148 148 % 10 = 8 So 82855-13-8 is a valid CAS Registry Number.