The CAS Registry Mumber 88078-64-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,8,0,7 and 8 respectively; the second part has 2 digits, 6 and 4 respectively. Calculate Digit Verification of CAS Registry Number 88078-64: (7*8)+(6*8)+(5*0)+(4*7)+(3*8)+(2*6)+(1*4)=172 172 % 10 = 2 So 88078-64-2 is a valid CAS Registry Number.