The CAS Registry Mumber 84928-86-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,4,9,2 and 8 respectively; the second part has 2 digits, 8 and 6 respectively. Calculate Digit Verification of CAS Registry Number 84928-86: (7*8)+(6*4)+(5*9)+(4*2)+(3*8)+(2*8)+(1*6)=179 179 % 10 = 9 So 84928-86-9 is a valid CAS Registry Number.