The CAS Registry Mumber 80702-44-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,0,7,0 and 2 respectively; the second part has 2 digits, 4 and 4 respectively. Calculate Digit Verification of CAS Registry Number 80702-44: (7*8)+(6*0)+(5*7)+(4*0)+(3*2)+(2*4)+(1*4)=109 109 % 10 = 9 So 80702-44-9 is a valid CAS Registry Number.