The CAS Registry Mumber 4397-07-3 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,3,9 and 7 respectively; the second part has 2 digits, 0 and 7 respectively. Calculate Digit Verification of CAS Registry Number 4397-07: (6*4)+(5*3)+(4*9)+(3*7)+(2*0)+(1*7)=103 103 % 10 = 3 So 4397-07-3 is a valid CAS Registry Number.