The CAS Registry Mumber 24179-83-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,4,1,7 and 9 respectively; the second part has 2 digits, 8 and 3 respectively. Calculate Digit Verification of CAS Registry Number 24179-83: (7*2)+(6*4)+(5*1)+(4*7)+(3*9)+(2*8)+(1*3)=117 117 % 10 = 7 So 24179-83-7 is a valid CAS Registry Number.