The CAS Registry Mumber 111299-34-4 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,1,2,9 and 9 respectively; the second part has 2 digits, 3 and 4 respectively. Calculate Digit Verification of CAS Registry Number 111299-34: (8*1)+(7*1)+(6*1)+(5*2)+(4*9)+(3*9)+(2*3)+(1*4)=104 104 % 10 = 4 So 111299-34-4 is a valid CAS Registry Number.