Printing DATA found in another column with text in front of it on a different column.

Hello I need some help with something extremely simple.

I have 4 columns

A B C D

Column A has a number, lets say 5 now i need column D to print the data in column A with the word B in front of the number and DF after the number, B5DF


Example

A B C D
5 B5DF
6 B6DF
7 B7DF

I can't use cell formatting. I need a formula that will lookup the value on column A print it in column C and add the letters before and after the number.