The CAS Registry Mumber 723-50-2 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 7,2 and 3 respectively; the second part has 2 digits, 5 and 0 respectively. Calculate Digit Verification of CAS Registry Number 723-50: (5*7)+(4*2)+(3*3)+(2*5)+(1*0)=62 62 % 10 = 2 So 723-50-2 is a valid CAS Registry Number.