DUP

Calculator Key: Enter

Member Of Menu: 
Stack
Argument Types: 
Any
Result Type(s): 
Any
Invertible: 
No
Valid In Expression: 
No
Stack Diagram: 
Item1 → Item1 Item1

This operation creates a copy of the item at the top of the stack and pushes that copy onto the stack.

Note that the "Enter" key on the calculator executes the DUP operation if there is no entry in progress. If there is an entry in progress, then DUP is not executed and instead the entry is parsed.