The CAS Registry Mumber 82670-82-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,2,6,7 and 0 respectively; the second part has 2 digits, 8 and 2 respectively. Calculate Digit Verification of CAS Registry Number 82670-82: (7*8)+(6*2)+(5*6)+(4*7)+(3*0)+(2*8)+(1*2)=144 144 % 10 = 4 So 82670-82-4 is a valid CAS Registry Number.