The CAS Registry Mumber 112900-11-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,2,9,0 and 0 respectively; the second part has 2 digits, 1 and 1 respectively. Calculate Digit Verification of CAS Registry Number 112900-11: (8*1)+(7*1)+(6*2)+(5*9)+(4*0)+(3*0)+(2*1)+(1*1)=75 75 % 10 = 5 So 112900-11-5 is a valid CAS Registry Number.