Keeping Leading Zeroes

Usual apologies if this is dumb q, I am not a power user, Excel is simply a means to an end for me!

OK.... Column A contains product codes. These are of the format: 123/1234, i.e. 3 digits, a slash, 4 digits

In order to get records into my database, I need to remove the slash, so there are just 7 digits (the match field is structured this way in the database). Unfortunately, some product codes have leading zeros, e.g. 058/1234. Even if I format the cells as 'text', removing the slash changes the cell content to '581234'. How can I make it still say '0581234'?

I just noticed that if I delete an individual slash manually, the zeroes are retained. How can I make it behave like this for a whole column at a time?

Thanks!