The CAS Registry Mumber 110392-31-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,0,3,9 and 2 respectively; the second part has 2 digits, 3 and 1 respectively. Calculate Digit Verification of CAS Registry Number 110392-31: (8*1)+(7*1)+(6*0)+(5*3)+(4*9)+(3*2)+(2*3)+(1*1)=79 79 % 10 = 9 So 110392-31-9 is a valid CAS Registry Number.