The CAS Registry Mumber 93343-72-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,3,3,4 and 3 respectively; the second part has 2 digits, 7 and 2 respectively. Calculate Digit Verification of CAS Registry Number 93343-72: (7*9)+(6*3)+(5*3)+(4*4)+(3*3)+(2*7)+(1*2)=137 137 % 10 = 7 So 93343-72-7 is a valid CAS Registry Number.