A pharmaceutical company is going to issue new ID codes to its employees. Each code will have three letters followed by one digit. The letters \( H \) and \( I \) and the digits 2,4,6, and 8 will not be used. So, there are 24 letters and 6 digits that will be used. Assume that the letters can be repeated. How many employee ID codes can be generated?
\( \square \)
employee ID codes