The CAS Registry Mumber 24016-73-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,4,0,1 and 6 respectively; the second part has 2 digits, 7 and 3 respectively. Calculate Digit Verification of CAS Registry Number 24016-73: (7*2)+(6*4)+(5*0)+(4*1)+(3*6)+(2*7)+(1*3)=77 77 % 10 = 7 So 24016-73-7 is a valid CAS Registry Number.