The CAS Registry Mumber 69980-30-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,9,9,8 and 0 respectively; the second part has 2 digits, 3 and 0 respectively. Calculate Digit Verification of CAS Registry Number 69980-30: (7*6)+(6*9)+(5*9)+(4*8)+(3*0)+(2*3)+(1*0)=179 179 % 10 = 9 So 69980-30-9 is a valid CAS Registry Number.