The CAS Registry Mumber 143723-86-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,4,3,7,2 and 3 respectively; the second part has 2 digits, 8 and 6 respectively. Calculate Digit Verification of CAS Registry Number 143723-86: (8*1)+(7*4)+(6*3)+(5*7)+(4*2)+(3*3)+(2*8)+(1*6)=128 128 % 10 = 8 So 143723-86-8 is a valid CAS Registry Number.