The CAS Registry Mumber 52311-85-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,2,3,1 and 1 respectively; the second part has 2 digits, 8 and 5 respectively. Calculate Digit Verification of CAS Registry Number 52311-85: (7*5)+(6*2)+(5*3)+(4*1)+(3*1)+(2*8)+(1*5)=90 90 % 10 = 0 So 52311-85-0 is a valid CAS Registry Number.