The CAS Registry Mumber 118499-09-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,8,4,9 and 9 respectively; the second part has 2 digits, 0 and 9 respectively. Calculate Digit Verification of CAS Registry Number 118499-09: (8*1)+(7*1)+(6*8)+(5*4)+(4*9)+(3*9)+(2*0)+(1*9)=155 155 % 10 = 5 So 118499-09-5 is a valid CAS Registry Number.