The CAS Registry Mumber 22043-09-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,2,0,4 and 3 respectively; the second part has 2 digits, 0 and 9 respectively. Calculate Digit Verification of CAS Registry Number 22043-09: (7*2)+(6*2)+(5*0)+(4*4)+(3*3)+(2*0)+(1*9)=60 60 % 10 = 0 So 22043-09-0 is a valid CAS Registry Number.