The CAS Registry Mumber 80883-07-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,0,8,8 and 3 respectively; the second part has 2 digits, 0 and 7 respectively. Calculate Digit Verification of CAS Registry Number 80883-07: (7*8)+(6*0)+(5*8)+(4*8)+(3*3)+(2*0)+(1*7)=144 144 % 10 = 4 So 80883-07-4 is a valid CAS Registry Number.