Hh:mm:ss:msms Timer with one Line

How do I...?
1

Hello, I would like to know how that one line continue with adding milliseconds? Can someone please solve this?

Do = ToString(floor(Variable(t)/3600))+"h "+ToString(floor(Variable(t)/60)-floor(Variable(t)/3600)*60)+"m "+ToString(floor(Variable(t))-floor(Variable(t)/60)*60)+“s” to the text of EventTimer