Removing dashes in excel

I have a 12 digit code with a dash after the 4th and 8th digit. I need to remove the dash but when I select edit remove it changes the number to an error. For example, the cell 1234-5678-9012 would now look like 1.23578E+11. The column width isn’t the problem. This doesn’t happen if the cell is only 11 digits long.