The CAS Registry Mumber 80077-17-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,0,0,7 and 7 respectively; the second part has 2 digits, 1 and 7 respectively. Calculate Digit Verification of CAS Registry Number 80077-17: (7*8)+(6*0)+(5*0)+(4*7)+(3*7)+(2*1)+(1*7)=114 114 % 10 = 4 So 80077-17-4 is a valid CAS Registry Number.