The CAS Registry Mumber 82381-01-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,2,3,8 and 1 respectively; the second part has 2 digits, 0 and 1 respectively. Calculate Digit Verification of CAS Registry Number 82381-01: (7*8)+(6*2)+(5*3)+(4*8)+(3*1)+(2*0)+(1*1)=119 119 % 10 = 9 So 82381-01-9 is a valid CAS Registry Number.