The CAS Registry Mumber 54898-50-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,4,8,9 and 8 respectively; the second part has 2 digits, 5 and 0 respectively. Calculate Digit Verification of CAS Registry Number 54898-50: (7*5)+(6*4)+(5*8)+(4*9)+(3*8)+(2*5)+(1*0)=169 169 % 10 = 9 So 54898-50-9 is a valid CAS Registry Number.