If you are using Emacs with the X window system, there is an easier way to move small amounts of data into and out of the calculator: Use the mouse-oriented cut and paste facilities of X.
The default bindings for a three-button mouse cause the left button to move the Emacs cursor to the given place, the right button to select the text between the cursor and the clicked location, and the middle button to yank the selection into the buffer at the clicked location. So, if you have a Calc window and an editing window on your Emacs screen, you can use left-click/right-click to select a number, vector, or formula from one window, then middle-click to paste that value into the other window. When you paste text into the Calc window, Calc interprets it as an algebraic entry. It doesn't matter where you click in the Calc window; the new value is always pushed onto the top of the stack.
The xterm program that is typically used for general-purpose
shell windows in X interprets the mouse buttons in the same way.
So you can use the mouse to move data between Calc and any other
Unix program. One nice feature of xterm is that a double
left-click selects one word, and a triple left-click selects a
whole line. So you can usually transfer a single number into Calc
just by double-clicking on it in the shell, then middle-clicking
in the Calc window.