The CAS Registry Mumber 85319-52-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,5,3,1 and 9 respectively; the second part has 2 digits, 5 and 2 respectively. Calculate Digit Verification of CAS Registry Number 85319-52: (7*8)+(6*5)+(5*3)+(4*1)+(3*9)+(2*5)+(1*2)=144 144 % 10 = 4 So 85319-52-4 is a valid CAS Registry Number.