The CAS Registry Mumber 72433-39-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,2,4,3 and 3 respectively; the second part has 2 digits, 3 and 9 respectively. Calculate Digit Verification of CAS Registry Number 72433-39: (7*7)+(6*2)+(5*4)+(4*3)+(3*3)+(2*3)+(1*9)=117 117 % 10 = 7 So 72433-39-7 is a valid CAS Registry Number.