The CAS Registry Mumber 112547-42-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,2,5,4 and 7 respectively; the second part has 2 digits, 4 and 2 respectively. Calculate Digit Verification of CAS Registry Number 112547-42: (8*1)+(7*1)+(6*2)+(5*5)+(4*4)+(3*7)+(2*4)+(1*2)=99 99 % 10 = 9 So 112547-42-9 is a valid CAS Registry Number.