The CAS Registry Mumber 116507-50-7 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,6,5,0 and 7 respectively; the second part has 2 digits, 5 and 0 respectively. Calculate Digit Verification of CAS Registry Number 116507-50: (8*1)+(7*1)+(6*6)+(5*5)+(4*0)+(3*7)+(2*5)+(1*0)=107 107 % 10 = 7 So 116507-50-7 is a valid CAS Registry Number.