The CAS Registry Mumber 111039-42-0 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,1,0,3 and 9 respectively; the second part has 2 digits, 4 and 2 respectively. Calculate Digit Verification of CAS Registry Number 111039-42: (8*1)+(7*1)+(6*1)+(5*0)+(4*3)+(3*9)+(2*4)+(1*2)=70 70 % 10 = 0 So 111039-42-0 is a valid CAS Registry Number.