The CAS Registry Mumber 53241-85-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,3,2,4 and 1 respectively; the second part has 2 digits, 8 and 5 respectively. Calculate Digit Verification of CAS Registry Number 53241-85: (7*5)+(6*3)+(5*2)+(4*4)+(3*1)+(2*8)+(1*5)=103 103 % 10 = 3 So 53241-85-3 is a valid CAS Registry Number.