The CAS Registry Mumber 116206-72-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,6,2,0 and 6 respectively; the second part has 2 digits, 7 and 2 respectively. Calculate Digit Verification of CAS Registry Number 116206-72: (8*1)+(7*1)+(6*6)+(5*2)+(4*0)+(3*6)+(2*7)+(1*2)=95 95 % 10 = 5 So 116206-72-5 is a valid CAS Registry Number.