What does the third number mean in my clock face?

[423536271827]

I have a clock face that shows something like this:

12

58

37

What does the third number mean?

[LZeeW]

@423536271827   I never use an Alta HR, but there is an image in this Tech Advisor review that makes it sound like this is an hours, minutes, seconds clock face.

[Diane175]

I think that's the seconds - you should be able to go through the app and customize the clock face however you prefer