The CAS Registry Mumber 220732-34-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 2,2,0,7,3 and 2 respectively; the second part has 2 digits, 3 and 4 respectively. Calculate Digit Verification of CAS Registry Number 220732-34: (8*2)+(7*2)+(6*0)+(5*7)+(4*3)+(3*2)+(2*3)+(1*4)=93 93 % 10 = 3 So 220732-34-3 is a valid CAS Registry Number.