The CAS Registry Mumber 116280-65-0 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,6,2,8 and 0 respectively; the second part has 2 digits, 6 and 5 respectively. Calculate Digit Verification of CAS Registry Number 116280-65: (8*1)+(7*1)+(6*6)+(5*2)+(4*8)+(3*0)+(2*6)+(1*5)=110 110 % 10 = 0 So 116280-65-0 is a valid CAS Registry Number.