The CAS Registry Mumber 99286-86-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,9,2,8 and 6 respectively; the second part has 2 digits, 8 and 6 respectively. Calculate Digit Verification of CAS Registry Number 99286-86: (7*9)+(6*9)+(5*2)+(4*8)+(3*6)+(2*8)+(1*6)=199 199 % 10 = 9 So 99286-86-9 is a valid CAS Registry Number.