I need help in creating formula for multiple arguments.

Column A: Lists a Number
Column B: Defines Number

For example:

CPT Description
43262 Upper Endo
43268 ERCP
45380 Colonoscopy
71020 CXR
80061 Lipid
80074 Hep Panel
80162 Dig
82105 AFP



Column C list number 43363, 43368, etc. or another number not yet
defined.

Goal: To list in Column D on the definition listed in Column B.

Please note, there are 60 numbers listed in Column A in with 60
Definitions.

Currently these are on 2 separate sheets, but I could merge them for
ease of the formula.


I tried the following with manually entering the definition for each
number...Unsuccessful.

=IF(C4=43242,"Upper
Endo",IF(C4=43268,"ERCP",IF(C4=71020,"CXR",IF(C4=7 1035,"CXR",IF(C4=80061,"Lipids",IF(C4=82378,"CEA", IF(C4=82465,"Chol",IF(C4=82728,"Fe",IF(C4=82947,"G lu",IF(C4=82977,"GTT",IF(C4=83036,"Gly
Hg",IF(C4=83540,"Iron",IF(C4=83550,"Iron
Binding",IF(C4=83700,"Lipoprotein",IF(C4=83701,"Li poprotein",IF(C4=83718,"HDL"))))))))))))))

Thanks