The CAS Registry Mumber 116454-16-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,6,4,5 and 4 respectively; the second part has 2 digits, 1 and 6 respectively. Calculate Digit Verification of CAS Registry Number 116454-16: (8*1)+(7*1)+(6*6)+(5*4)+(4*5)+(3*4)+(2*1)+(1*6)=111 111 % 10 = 1 So 116454-16-1 is a valid CAS Registry Number.