The CAS Registry Mumber 113341-50-7 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,3,3,4 and 1 respectively; the second part has 2 digits, 5 and 0 respectively. Calculate Digit Verification of CAS Registry Number 113341-50: (8*1)+(7*1)+(6*3)+(5*3)+(4*4)+(3*1)+(2*5)+(1*0)=77 77 % 10 = 7 So 113341-50-7 is a valid CAS Registry Number.