The CAS Registry Mumber 2474-25-1 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 2,4,7 and 4 respectively; the second part has 2 digits, 2 and 5 respectively. Calculate Digit Verification of CAS Registry Number 2474-25: (6*2)+(5*4)+(4*7)+(3*4)+(2*2)+(1*5)=81 81 % 10 = 1 So 2474-25-1 is a valid CAS Registry Number.