The CAS Registry Mumber 144918-26-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,4,4,9,1 and 8 respectively; the second part has 2 digits, 2 and 6 respectively. Calculate Digit Verification of CAS Registry Number 144918-26: (8*1)+(7*4)+(6*4)+(5*9)+(4*1)+(3*8)+(2*2)+(1*6)=143 143 % 10 = 3 So 144918-26-3 is a valid CAS Registry Number.