The CAS Registry Mumber 22243-32-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,2,2,4 and 3 respectively; the second part has 2 digits, 3 and 2 respectively. Calculate Digit Verification of CAS Registry Number 22243-32: (7*2)+(6*2)+(5*2)+(4*4)+(3*3)+(2*3)+(1*2)=69 69 % 10 = 9 So 22243-32-9 is a valid CAS Registry Number.