The CAS Registry Mumber 143837-97-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,4,3,8,3 and 7 respectively; the second part has 2 digits, 9 and 7 respectively. Calculate Digit Verification of CAS Registry Number 143837-97: (8*1)+(7*4)+(6*3)+(5*8)+(4*3)+(3*7)+(2*9)+(1*7)=152 152 % 10 = 2 So 143837-97-2 is a valid CAS Registry Number.