To place a black square before equations while also displaying line numbers in LaTeX, the amssymb package must be included with the command \usepackage{amssymb}. The specific command for the black square is \blacksquare. To achieve the desired formatting of having the black square on the left side of the equation and the equation number on the right, additional customization is required, particularly for only a select few equations. The discussion emphasizes the urgency of the request due to an impending deadline for a term paper.