The CAS Registry Mumber 53250-85-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,3,2,5 and 0 respectively; the second part has 2 digits, 8 and 5 respectively. Calculate Digit Verification of CAS Registry Number 53250-85: (7*5)+(6*3)+(5*2)+(4*5)+(3*0)+(2*8)+(1*5)=104 104 % 10 = 4 So 53250-85-4 is a valid CAS Registry Number.