What is an abbreviation for hour and minutes not using letters?

You can't abbreviate hours and minutes without using letters.

Here's why:

* Symbols: While we have symbols for things like seconds (s), minutes (min), and hours (h), there aren't standard symbols for combining them.

* Clarity: Using numbers alone could lead to confusion. For example, "123" could mean 12 hours and 3 minutes, or 1 hour and 23 minutes.

* Common Usage: The standard way to abbreviate time is to use "h" for hours and "min" for minutes.

Let me know if you have any other questions!