The CAS Registry Mumber 82878-52-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,2,8,7 and 8 respectively; the second part has 2 digits, 5 and 2 respectively. Calculate Digit Verification of CAS Registry Number 82878-52: (7*8)+(6*2)+(5*8)+(4*7)+(3*8)+(2*5)+(1*2)=172 172 % 10 = 2 So 82878-52-2 is a valid CAS Registry Number.