The CAS Registry Mumber 55284-14-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,5,2,8 and 4 respectively; the second part has 2 digits, 1 and 4 respectively. Calculate Digit Verification of CAS Registry Number 55284-14: (7*5)+(6*5)+(5*2)+(4*8)+(3*4)+(2*1)+(1*4)=125 125 % 10 = 5 So 55284-14-5 is a valid CAS Registry Number.