The CAS Registry Mumber 24920-49-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,4,9,2 and 0 respectively; the second part has 2 digits, 4 and 9 respectively. Calculate Digit Verification of CAS Registry Number 24920-49: (7*2)+(6*4)+(5*9)+(4*2)+(3*0)+(2*4)+(1*9)=108 108 % 10 = 8 So 24920-49-8 is a valid CAS Registry Number.