The CAS Registry Mumber 50722-97-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,0,7,2 and 2 respectively; the second part has 2 digits, 9 and 7 respectively. Calculate Digit Verification of CAS Registry Number 50722-97: (7*5)+(6*0)+(5*7)+(4*2)+(3*2)+(2*9)+(1*7)=109 109 % 10 = 9 So 50722-97-9 is a valid CAS Registry Number.