The CAS Registry Mumber 54245-61-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,4,2,4 and 5 respectively; the second part has 2 digits, 6 and 1 respectively. Calculate Digit Verification of CAS Registry Number 54245-61: (7*5)+(6*4)+(5*2)+(4*4)+(3*5)+(2*6)+(1*1)=113 113 % 10 = 3 So 54245-61-3 is a valid CAS Registry Number.