The CAS Registry Mumber 120807-81-0 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,0,8,0 and 7 respectively; the second part has 2 digits, 8 and 1 respectively. Calculate Digit Verification of CAS Registry Number 120807-81: (8*1)+(7*2)+(6*0)+(5*8)+(4*0)+(3*7)+(2*8)+(1*1)=100 100 % 10 = 0 So 120807-81-0 is a valid CAS Registry Number.