We can tell the time without saying AM and PM though - for this, we use the 24 hour clock. The 24 hour clock always uses 4 digits, and we use this system most often with digital clocks.

Black in colour, this digital alarm clock has a simple and friendly design. It will display everything from your alarm details to the date and time on the screen. You can also see the temperature ...

Not that the present situation and the abundance of free time that many are experiencing has anything to do with [Leo Fernekes] all-transistor digital clock build, which he started a year ago ...

We can tell the time without saying AM and PM though - for this, we use the 24 hour clock. The 24 hour clock always uses 4 digits, and we use this system most often with digital clocks.