How do you enter the radio code for a BMW Z3 1998?

To enter the radio code for a 1998 BMW Z3, first, turn on the ignition and then the radio. If the radio prompts for a code, use the preset buttons (1-4) to input the code. For example, if the code is 1234, press button 1 once, button 2 twice, button 3 three times, and button 4 four times. After entering the correct code, the radio should unlock and resume normal functionality.