The CAS Registry Mumber 4925-53-5 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,9,2 and 5 respectively; the second part has 2 digits, 5 and 3 respectively. Calculate Digit Verification of CAS Registry Number 4925-53: (6*4)+(5*9)+(4*2)+(3*5)+(2*5)+(1*3)=105 105 % 10 = 5 So 4925-53-5 is a valid CAS Registry Number.