The CAS Registry Mumber 117416-11-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,7,4,1 and 6 respectively; the second part has 2 digits, 1 and 1 respectively. Calculate Digit Verification of CAS Registry Number 117416-11: (8*1)+(7*1)+(6*7)+(5*4)+(4*1)+(3*6)+(2*1)+(1*1)=102 102 % 10 = 2 So 117416-11-2 is a valid CAS Registry Number.