Hi Fireman,
You already have a great answer from mr. Graham Mayor, but i suggest an alternative solution using a very simple Custom Format:
Select column A for example, if this is your column with this code format, go to ribbon's Home tab, Numbers section, choose custom format, and place this custom format in Type section: "BC102014"#
Note that this custom format will only work with numbers, if you type text in that column, the prefix code will not be added. This means that you will be able to use the exact number you typed. If you type 11234 in a cell, after you press enter, the prefix will be added; when you select the cell, even if it will show BC10201411234, if you look in the formula bar, the cell contains only what you typed: 11234...
Cheers,
Catalin Bombea

Attached Files

Book1.xlsx (7.7 KB, 11 views)

Only glitch is that any entry that starts with a zero (0), for example 00123, does not add the zeroes.