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.

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.