The CAS Registry Mumber 24809-76-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,4,8,0 and 9 respectively; the second part has 2 digits, 7 and 6 respectively. Calculate Digit Verification of CAS Registry Number 24809-76: (7*2)+(6*4)+(5*8)+(4*0)+(3*9)+(2*7)+(1*6)=125 125 % 10 = 5 So 24809-76-5 is a valid CAS Registry Number.