The CAS Registry Mumber 4502-48-1 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,5,0 and 2 respectively; the second part has 2 digits, 4 and 8 respectively. Calculate Digit Verification of CAS Registry Number 4502-48: (6*4)+(5*5)+(4*0)+(3*2)+(2*4)+(1*8)=71 71 % 10 = 1 So 4502-48-1 is a valid CAS Registry Number.