Format from column to single cell

I am a macro beginner and I have a column of numbers that I need to reformat. I created a macro to copy/paste special/transpose to get the data into separate columns. I then used & to get them into one cell. I can only have five sets of # in each cell. The macro works but it replaces the previous set of accounts. Is this the best way to reformat these numbers? If so, how do I correct the macro so that it doesnt replace the data i already reformatted?

I have attached a sample spreadsheet. Hope it worked!

Thanks so much!