Excel Reference Cell using If Then Statements

I wanted to use a If Then statement for a column of individual cells. I wanted the cell reference to say, if Cell # = 1, then ea, if Cell # =2, then box. I wanted this for each individual cell for the column I am working on. So when I enter one of those numbers in one of the individual cells in the column, I would get the desired outcome of ea or box. This is the formula I am using, =IF(E5=1,"ea",IF(E5=2,"box",IF(E5=3,"case"))),  however when I use it for the next cell, it gives me a circular reference error. I wanted to use the same formula for each individual cell to reference the words ea or box.