Challenge: Generate a 64 in the display (RPN)

[Gerson W. Barbosa]

I beg to disagree. Quoting from the OP, my underlining:

Quote:Your challenge is to take a classic RPN machine in an unknown stack circumstance and generate a 64 in the X register.
...

Who can come up with the shortest set of steps ?

Notice Gene says “a classic RPN machine”, not most RPN machines. No comment needed for his last statement. I don’t care a straw for political correctness, but I would say the award goes to Valentín Albillo, who was the first to point out to a two-step solution on the HP-42S. Sometimes it is important to find a solution quickly, even if it is not optimal, so a special award should go to Bruce. Sometimes a generic solution is desirable, then a special award should go to Didier.
Anyway, we all win when we participate in these challenges. Keep them coming!