The CAS Registry Mumber 111742-72-4 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,1,7,4 and 2 respectively; the second part has 2 digits, 7 and 2 respectively. Calculate Digit Verification of CAS Registry Number 111742-72: (8*1)+(7*1)+(6*1)+(5*7)+(4*4)+(3*2)+(2*7)+(1*2)=94 94 % 10 = 4 So 111742-72-4 is a valid CAS Registry Number.