The CAS Registry Mumber 120266-80-0 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,0,2,6 and 6 respectively; the second part has 2 digits, 8 and 0 respectively. Calculate Digit Verification of CAS Registry Number 120266-80: (8*1)+(7*2)+(6*0)+(5*2)+(4*6)+(3*6)+(2*8)+(1*0)=90 90 % 10 = 0 So 120266-80-0 is a valid CAS Registry Number.