Program using directly the stack

[SimonP]

I just received my HP Prime and I try to do a very simple program using the result of a calculation, displayed on the first line of the stack.
How to do it?
My Example:
After a few manipulations, I have the result 125.
I would like to apply the command "R->B" to easily convert and display this value in hexadecimal.
This to avoid to tip: ALPHA R SHIFT 9 -> ALPHA B ENTER

Thanks to help me.