The CAS Registry Mumber 53201-80-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,3,2,0 and 1 respectively; the second part has 2 digits, 8 and 0 respectively. Calculate Digit Verification of CAS Registry Number 53201-80: (7*5)+(6*3)+(5*2)+(4*0)+(3*1)+(2*8)+(1*0)=82 82 % 10 = 2 So 53201-80-2 is a valid CAS Registry Number.