The CAS Registry Mumber 116441-23-7 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,6,4,4 and 1 respectively; the second part has 2 digits, 2 and 3 respectively. Calculate Digit Verification of CAS Registry Number 116441-23: (8*1)+(7*1)+(6*6)+(5*4)+(4*4)+(3*1)+(2*2)+(1*3)=97 97 % 10 = 7 So 116441-23-7 is a valid CAS Registry Number.