The CAS Registry Mumber 84669-88-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,4,6,6 and 9 respectively; the second part has 2 digits, 8 and 8 respectively. Calculate Digit Verification of CAS Registry Number 84669-88: (7*8)+(6*4)+(5*6)+(4*6)+(3*9)+(2*8)+(1*8)=185 185 % 10 = 5 So 84669-88-5 is a valid CAS Registry Number.